diff --git a/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFModelState.java b/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFModelState.java
index 72b7e21f..49501a96 100644
--- a/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFModelState.java
+++ b/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFModelState.java
@@ -20,7 +20,7 @@
 import org.eclipse.glsp.server.model.GModelState;
 
 public interface EMFModelState extends GModelState {
-   void setEditingDomain(EditingDomain editingDomain);
+   void setEditingDomain(EditingDomain editingDomain, String subclientId);
 
    EditingDomain getEditingDomain();
 
diff --git a/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFModelStateImpl.java b/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFModelStateImpl.java
index 89e49df4..d2292089 100644
--- a/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFModelStateImpl.java
+++ b/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFModelStateImpl.java
@@ -17,6 +17,7 @@
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.eclipse.emf.common.command.BasicCommandStack;
 import org.eclipse.emf.common.command.CommandStack;
 import org.eclipse.emf.common.util.EList;
 import org.eclipse.emf.ecore.resource.Resource;
@@ -24,6 +25,7 @@
 import org.eclipse.emf.edit.domain.EditingDomain;
 import org.eclipse.glsp.graph.GModelIndex;
 import org.eclipse.glsp.graph.GModelRoot;
+import org.eclipse.glsp.server.command.CommandStackManager;
 import org.eclipse.glsp.server.model.DefaultGModelState;
 import org.eclipse.glsp.server.session.ClientSession;
 import org.eclipse.glsp.server.session.ClientSessionListener;
@@ -50,6 +52,9 @@ public class EMFModelStateImpl extends DefaultGModelState implements EMFModelSta
    @Inject
    protected ClientSessionManager clientSessionManager;
 
+   @Inject
+   protected CommandStackManager commandStackManager;
+
    @Inject
    protected EMFIdGenerator idGenerator;
 
@@ -62,9 +67,9 @@ public void init() {
    }
 
    @Override
-   public void setEditingDomain(final EditingDomain editingDomain) {
+   public void setEditingDomain(final EditingDomain editingDomain, final String subclientId) {
       this.editingDomain = editingDomain;
-      setCommandStack(this.editingDomain.getCommandStack());
+      commandStackManager.setCommandStack(this.editingDomain.getCommandStack(), subclientId);
    }
 
    @Override
@@ -107,8 +112,12 @@ protected void closeResourceSet() {
          }
       }
       if (result) {
-         commandStack.flush();
-         saveIsDone();
+         commandStackManager.getAllCommandStacks().forEach(commandStack -> {
+            commandStack.flush();
+            if (commandStack instanceof BasicCommandStack) {
+               ((BasicCommandStack) commandStack).saveIsDone();
+            }
+         });
       }
    }
 
diff --git a/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFSourceModelStorage.java b/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFSourceModelStorage.java
index e2085f93..bad013e8 100644
--- a/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFSourceModelStorage.java
+++ b/plugins/org.eclipse.glsp.server.emf/src/org/eclipse/glsp/server/emf/EMFSourceModelStorage.java
@@ -56,17 +56,17 @@ public void loadSourceModel(final RequestModelAction action) {
          .orElseThrow(() -> new GLSPServerException("No source URI given to load model!"));
       URI resourceURI = URI.createFileURI(sourceURI);
 
-      EditingDomain editingDomain = getOrCreateEditingDomain();
+      EditingDomain editingDomain = getOrCreateEditingDomain(action.getSubclientId());
       doLoadSourceModel(editingDomain.getResourceSet(), resourceURI, action);
    }
 
-   protected EditingDomain getOrCreateEditingDomain() {
+   protected EditingDomain getOrCreateEditingDomain(final String subclientId) {
       if (modelState.getEditingDomain() != null) {
          return modelState.getEditingDomain();
       }
       EditingDomain editingDomain = editingDomainFactory.createEditingDomain();
       setupResourceSet(editingDomain.getResourceSet());
-      modelState.setEditingDomain(editingDomain);
+      modelState.setEditingDomain(editingDomain, subclientId);
       return editingDomain;
    }
 
diff --git a/plugins/org.eclipse.glsp.server/META-INF/MANIFEST.MF b/plugins/org.eclipse.glsp.server/META-INF/MANIFEST.MF
index c0a84e05..639a2700 100644
--- a/plugins/org.eclipse.glsp.server/META-INF/MANIFEST.MF
+++ b/plugins/org.eclipse.glsp.server/META-INF/MANIFEST.MF
@@ -34,6 +34,7 @@ Export-Package: org.eclipse.glsp.server.actions,
  org.eclipse.glsp.server.features.validation,
  org.eclipse.glsp.server.gmodel,
  org.eclipse.glsp.server.gson,
+ org.eclipse.glsp.server.command,
  org.eclipse.glsp.server.internal.actions;x-internal:=true,
  org.eclipse.glsp.server.internal.di.scope;x-internal:=true,
  org.eclipse.glsp.server.internal.diagram;x-internal:=true,
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/actions/Action.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/actions/Action.java
index 724fa2f9..1ea32038 100644
--- a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/actions/Action.java
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/actions/Action.java
@@ -40,9 +40,20 @@ public abstract class Action {
     */
    private boolean receivedFromClient;
 
-   public Action(final String kind) {
+   /**
+    * Unique identifier specifying the initiator of the action in a collaboration session.
+    * This value is initialized on the initating client.
+    */
+   private String subclientId;
+
+   public Action(final String kind, final String subclientId) {
       super();
       this.kind = kind;
+      this.subclientId = subclientId;
+   }
+
+   public Action(final String kind) {
+      this(kind, null);
    }
 
    public String getKind() { return kind; }
@@ -51,6 +62,8 @@ public Action(final String kind) {
 
    public void setReceivedFromClient(final boolean receivedFromClient) { this.receivedFromClient = receivedFromClient; }
 
+   public String getSubclientId() { return subclientId; }
+
    @Override
    public String toString() {
       StringBuilder builder = new StringBuilder();
@@ -60,4 +73,11 @@ public String toString() {
       return builder.toString();
    }
 
+   public static Action addSubclientId(final Action initialAction, final Action extendedAction) {
+      if (initialAction.getSubclientId() != null) {
+         extendedAction.subclientId = initialAction.subclientId;
+      }
+      return extendedAction;
+   }
+
 }
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/actions/SaveModelActionHandler.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/actions/SaveModelActionHandler.java
index 4bd58ea2..18fd9952 100644
--- a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/actions/SaveModelActionHandler.java
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/actions/SaveModelActionHandler.java
@@ -49,7 +49,8 @@ public List<Action> executeAction(final SaveModelAction action) {
       } finally {
          modelSourceWatcher.ifPresent(watcher -> watcher.continueWatching());
       }
-      return listOf(new SetDirtyStateAction(modelState.isDirty(), SetDirtyStateAction.Reason.SAVE));
+      return listOf(
+         new SetDirtyStateAction(modelState.isDirty(), SetDirtyStateAction.Reason.SAVE));
    }
 
 }
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/command/CommandStackFactory.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/command/CommandStackFactory.java
new file mode 100644
index 00000000..9068ba62
--- /dev/null
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/command/CommandStackFactory.java
@@ -0,0 +1,7 @@
+package org.eclipse.glsp.server.command;
+
+import org.eclipse.emf.common.command.CommandStack;
+
+public interface CommandStackFactory {
+    CommandStack createCommandStack();
+}
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/command/CommandStackManager.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/command/CommandStackManager.java
new file mode 100644
index 00000000..2d810828
--- /dev/null
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/command/CommandStackManager.java
@@ -0,0 +1,13 @@
+package org.eclipse.glsp.server.command;
+
+import org.eclipse.emf.common.command.CommandStack;
+
+import java.util.List;
+
+public interface CommandStackManager {
+    CommandStack getOrCreateCommandStack(String subclientId);
+
+    List<CommandStack> getAllCommandStacks();
+
+    void setCommandStack(CommandStack commandStack, String subclientId);
+}
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/command/DefaultCommandStackManager.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/command/DefaultCommandStackManager.java
new file mode 100644
index 00000000..53c64ded
--- /dev/null
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/command/DefaultCommandStackManager.java
@@ -0,0 +1,53 @@
+package org.eclipse.glsp.server.command;
+
+import com.google.inject.Inject;
+import org.eclipse.emf.common.command.CommandStack;
+import org.eclipse.glsp.server.utils.CollaborationUtil;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class DefaultCommandStackManager implements CommandStackManager {
+
+    @Inject
+    CommandStackFactory factory;
+
+    // subclientId, CommandStack
+    protected Map<String, CommandStack> commandStackMap = new HashMap<>();
+
+    @Override
+    public CommandStack getOrCreateCommandStack(final String subclientId) {
+        String subclientIdOrFallback = getSubclientIdOrFallback(subclientId);
+        if (commandStackMap.containsKey(subclientIdOrFallback)) {
+            return commandStackMap.get(subclientIdOrFallback);
+        }
+
+        CommandStack commandStack = factory.createCommandStack();
+        commandStackMap.put(subclientIdOrFallback, commandStack);
+        return commandStack;
+    }
+
+    @Override
+    public List<CommandStack> getAllCommandStacks() {
+        return new ArrayList<>(commandStackMap.values());
+    }
+
+    @Override
+    public void setCommandStack(final CommandStack commandStack, final String subclientId) {
+        String subclientIdOrFallback = getSubclientIdOrFallback(subclientId);
+        if (commandStackMap.containsKey(subclientIdOrFallback)) {
+            commandStackMap.get(subclientIdOrFallback).flush();
+        }
+        commandStackMap.put(subclientIdOrFallback, commandStack);
+    }
+
+    private String getSubclientIdOrFallback(final String subclientId) {
+        if (subclientId != null) {
+            return subclientId;
+        }
+        return CollaborationUtil.FALLBACK_SUBCLIENT_ID;
+    }
+
+}
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/di/DiagramModule.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/di/DiagramModule.java
index 25c601a2..5ab01829 100644
--- a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/di/DiagramModule.java
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/di/DiagramModule.java
@@ -62,10 +62,14 @@
 import org.eclipse.glsp.server.gson.GraphGsonConfigurationFactory;
 import org.eclipse.glsp.server.internal.actions.DefaultActionDispatcher;
 import org.eclipse.glsp.server.internal.actions.DefaultActionHandlerRegistry;
+import org.eclipse.glsp.server.command.CommandStackFactory;
+import org.eclipse.glsp.server.command.CommandStackManager;
+import org.eclipse.glsp.server.command.DefaultCommandStackManager;
 import org.eclipse.glsp.server.internal.diagram.DefaultServerConfigurationContribution;
 import org.eclipse.glsp.server.internal.featues.directediting.DefaultContextEditValidatorRegistry;
 import org.eclipse.glsp.server.internal.featues.navigation.DefaultNavigationTargetProviderRegistry;
 import org.eclipse.glsp.server.internal.features.contextactions.DefaultContextActionsProviderRegistry;
+import org.eclipse.glsp.server.internal.gmodel.commandstack.GModelCommandStackFactory;
 import org.eclipse.glsp.server.internal.gson.DefaultGraphGsonConfigurationFactory;
 import org.eclipse.glsp.server.internal.operations.DefaultOperationHandlerRegistry;
 import org.eclipse.glsp.server.internal.toolpalette.DefaultToolPaletteItemProvider;
@@ -189,6 +193,10 @@ protected void configureBase() {
       bindOptionally(LayoutEngine.class, bindLayoutEngine());
       bindOptionally(GraphExtension.class, bindGraphExtension());
       bindOptionally(EdgeCreationChecker.class, bindEdgeCreationChecker());
+
+      // Command Stack
+      bind(CommandStackFactory.class).to(bindCommandStackFactory()).in(Singleton.class);
+      bind(CommandStackManager.class).to(bindCommandStackManager()).in(Singleton.class);
    }
 
    protected void bindDiagramType() {
@@ -328,5 +336,13 @@ protected Class<? extends EdgeCreationChecker> bindEdgeCreationChecker() {
       return null;
    }
 
+   protected Class<? extends CommandStackFactory> bindCommandStackFactory() {
+      return GModelCommandStackFactory.class;
+   }
+
+   protected Class<? extends CommandStackManager> bindCommandStackManager() {
+      return DefaultCommandStackManager.class;
+   }
+
    public abstract String getDiagramType();
 }
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/features/core/model/ModelSubmissionHandler.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/features/core/model/ModelSubmissionHandler.java
index 09a32589..8e15a563 100644
--- a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/features/core/model/ModelSubmissionHandler.java
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/features/core/model/ModelSubmissionHandler.java
@@ -88,7 +88,7 @@ public List<Action> submitInitialModel(final RequestModelAction requestAction) {
        * Therefore we temporarily store the action later retrival
        */
       this.requestModelAction = Optional.of(requestAction);
-      return submitModel();
+      return submitModel(requestAction.getSubclientId());
 
    }
 
@@ -126,7 +126,7 @@ public List<Action> submitModel() {
     * Returns a list of actions to directly update the client-side model without any server- or client-side layouting.
     * <p>
     * Typically {@link ActionHandler action handlers} don't invoke this method but use
-    * {@link #submitModel(String)}
+    * {@link #submitModel(String, String)}
     * instead, as this is only used to eventually submit the model on the client directly after all layouting is already
     * performed before. The only foreseen caller of this method is {@link ComputedBoundsActionHandler}.
     * </p>
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/features/core/model/RequestModelActionHandler.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/features/core/model/RequestModelActionHandler.java
index 42f4bec9..6d9d0ad1 100644
--- a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/features/core/model/RequestModelActionHandler.java
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/features/core/model/RequestModelActionHandler.java
@@ -64,20 +64,23 @@ public class RequestModelActionHandler extends AbstractActionHandler<RequestMode
 
    @Override
    public List<Action> executeAction(final RequestModelAction action) {
-      modelState.setClientOptions(action.getOptions());
-
-      boolean isReconnecting = ClientOptionsUtil.isReconnecting(action.getOptions());
-
-      ProgressMonitor monitor = notifyStartLoading();
-      if (isReconnecting) {
-         handleReconnect(action);
-      } else {
-         sourceModelStorage.loadSourceModel(action);
-      }
-      notifyFinishedLoading(monitor);
-
-      if (!isReconnecting) {
-         sourceModelWatcher.ifPresent(watcher -> watcher.startWatching());
+      // only reload if not initialized
+      if (!ClientOptionsUtil.disableReloadIsTrue(action.getOptions()) || modelState.getRoot() == null) {
+         modelState.setClientOptions(action.getOptions());
+
+         boolean isReconnecting = ClientOptionsUtil.isReconnecting(action.getOptions());
+
+         ProgressMonitor monitor = notifyStartLoading();
+         if (isReconnecting) {
+            handleReconnect(action);
+         } else {
+            sourceModelStorage.loadSourceModel(action);
+         }
+         notifyFinishedLoading(monitor);
+
+         if (!isReconnecting) {
+            sourceModelWatcher.ifPresent(watcher -> watcher.startWatching());
+         }
       }
 
       return modelSubmissionHandler.submitInitialModel(action);
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/gmodel/AbstractGModelCreateNodeOperationHandler.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/gmodel/AbstractGModelCreateNodeOperationHandler.java
index 960369e6..d7f21eb5 100644
--- a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/gmodel/AbstractGModelCreateNodeOperationHandler.java
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/gmodel/AbstractGModelCreateNodeOperationHandler.java
@@ -22,6 +22,7 @@
 import org.eclipse.glsp.graph.GModelElement;
 import org.eclipse.glsp.graph.GNode;
 import org.eclipse.glsp.graph.GPoint;
+import org.eclipse.glsp.server.actions.Action;
 import org.eclipse.glsp.server.actions.ActionDispatcher;
 import org.eclipse.glsp.server.actions.SelectAction;
 import org.eclipse.glsp.server.operations.AbstractCreateOperationHandler;
@@ -59,7 +60,10 @@ public void executeOperation(final CreateNodeOperation operation) {
          .map(location -> LayoutUtil.getRelativeLocation(location, container));
       GModelElement element = createNode(relativeLocation, operation.getArgs());
       container.getChildren().add(element);
-      actionDispatcher.dispatchAfterNextUpdate(new SelectAction(), new SelectAction(List.of(element.getId())));
+      actionDispatcher.dispatchAfterNextUpdate(
+              Action.addSubclientId(operation, new SelectAction()),
+              Action.addSubclientId(operation, new SelectAction(List.of(element.getId())))
+      );
    }
 
    /**
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/gmodel/GModelCreateNodeOperationHandler.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/gmodel/GModelCreateNodeOperationHandler.java
index 46a1f67d..e3921114 100644
--- a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/gmodel/GModelCreateNodeOperationHandler.java
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/gmodel/GModelCreateNodeOperationHandler.java
@@ -24,6 +24,7 @@
 import org.eclipse.glsp.graph.GModelElement;
 import org.eclipse.glsp.graph.GNode;
 import org.eclipse.glsp.graph.GPoint;
+import org.eclipse.glsp.server.actions.Action;
 import org.eclipse.glsp.server.actions.ActionDispatcher;
 import org.eclipse.glsp.server.actions.GhostElement;
 import org.eclipse.glsp.server.actions.SelectAction;
@@ -63,7 +64,12 @@ public void executeCreation(final CreateNodeOperation operation) {
       Optional<GPoint> relativeLocation = getRelativeLocation(container, absoluteLocation);
       GModelElement element = createNode(relativeLocation, operation.getArgs());
       container.getChildren().add(element);
-      actionDispatcher.dispatchAfterNextUpdate(SelectAction.addSelection(List.of(element.getId())));
+      actionDispatcher.dispatchAfterNextUpdate(
+              Action.addSubclientId(
+                      operation,
+                      SelectAction.addSelection(List.of(element.getId()))
+              )
+      );
    }
 
    protected Optional<GPoint> getLocation(final CreateNodeOperation operation) {
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/internal/actions/DefaultActionDispatcher.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/internal/actions/DefaultActionDispatcher.java
index 3b7ab73b..8dfbb6a3 100644
--- a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/internal/actions/DefaultActionDispatcher.java
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/internal/actions/DefaultActionDispatcher.java
@@ -40,6 +40,7 @@
 import org.eclipse.glsp.server.disposable.Disposable;
 import org.eclipse.glsp.server.features.core.model.SetModelAction;
 import org.eclipse.glsp.server.features.core.model.UpdateModelAction;
+import org.eclipse.glsp.server.model.GModelState;
 import org.eclipse.glsp.server.protocol.GLSPClient;
 import org.eclipse.glsp.server.utils.FutureUtil;
 
@@ -86,6 +87,10 @@ public class DefaultActionDispatcher extends Disposable implements ActionDispatc
    @Inject
    protected Provider<GLSPClient> client;
 
+   // use modelstate here to set subclient id
+   @Inject
+   protected GModelState modelState;
+
    public DefaultActionDispatcher() {
       this.initialize();
    }
@@ -206,10 +211,13 @@ protected List<CompletableFuture<Void>> runAction(final Action action) {
          throw new IllegalArgumentException("No handler registered for action: " + action);
       }
 
+      this.modelState.setParticipationID(action.getSubclientId());
+
       List<CompletableFuture<Void>> results = new ArrayList<>();
       for (final ActionHandler actionHandler : actionHandlers) {
          final List<Action> responses = actionHandler.execute(action).stream()
             .map(response -> ResponseAction.respond(action, response))
+            .map(response -> Action.addSubclientId(action, response))
             .collect(Collectors.toList());
          results.addAll(dispatchAll(responses));
       }
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/internal/gmodel/commandstack/GModelCommandStackFactory.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/internal/gmodel/commandstack/GModelCommandStackFactory.java
new file mode 100644
index 00000000..70fa53fe
--- /dev/null
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/internal/gmodel/commandstack/GModelCommandStackFactory.java
@@ -0,0 +1,11 @@
+package org.eclipse.glsp.server.internal.gmodel.commandstack;
+
+import org.eclipse.emf.common.command.CommandStack;
+import org.eclipse.glsp.server.command.CommandStackFactory;
+
+public class GModelCommandStackFactory implements CommandStackFactory  {
+    @Override
+    public CommandStack createCommandStack() {
+        return new GModelCommandStack();
+    }
+}
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/model/DefaultGModelState.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/model/DefaultGModelState.java
index a5991a80..7144bdae 100644
--- a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/model/DefaultGModelState.java
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/model/DefaultGModelState.java
@@ -24,6 +24,7 @@
 import org.eclipse.emf.common.command.CommandStack;
 import org.eclipse.glsp.graph.GModelIndex;
 import org.eclipse.glsp.graph.GModelRoot;
+import org.eclipse.glsp.server.command.CommandStackManager;
 import org.eclipse.glsp.server.di.ClientId;
 import org.eclipse.glsp.server.internal.gmodel.commandstack.GModelCommandStack;
 
@@ -37,16 +38,19 @@ public class DefaultGModelState implements GModelState {
    @ClientId
    protected String clientId;
 
+   @Inject
+   protected CommandStackManager commandStackManager;
+
    protected Map<String, String> options;
    protected final Map<String, Object> properties = new HashMap<>();
    protected GModelRoot currentModel;
-   protected CommandStack commandStack;
    protected String editMode;
    protected GModelIndex index = GModelIndex.empty();
+   protected String participationId;
 
    @Inject
    public void init() {
-      setCommandStack(new GModelCommandStack());
+      commandStackManager.setCommandStack(new GModelCommandStack(), null);
    }
 
    @Override
@@ -73,13 +77,6 @@ protected GModelIndex getOrUpdateIndex(final GModelRoot newRoot) {
 
    protected void setRoot(final GModelRoot newRoot) { this.currentModel = newRoot; }
 
-   protected void setCommandStack(final CommandStack commandStack) {
-      if (this.commandStack != null) {
-         this.commandStack.flush();
-      }
-      this.commandStack = commandStack;
-   }
-
    @Override
    public void setClientOptions(final Map<String, String> options) { this.options = options; }
 
@@ -88,6 +85,7 @@ protected void setCommandStack(final CommandStack commandStack) {
 
    @Override
    public void execute(final Command command) {
+      CommandStack commandStack = commandStackManager.getOrCreateCommandStack(this.participationId);
       if (commandStack != null) {
          commandStack.execute(command);
       }
@@ -95,16 +93,19 @@ public void execute(final Command command) {
 
    @Override
    public boolean canUndo() {
+      CommandStack commandStack = commandStackManager.getOrCreateCommandStack(this.participationId);
       return commandStack != null && commandStack.canUndo();
    }
 
    @Override
    public boolean canRedo() {
+      CommandStack commandStack = commandStackManager.getOrCreateCommandStack(this.participationId);
       return commandStack != null && commandStack.canRedo();
    }
 
    @Override
    public void undo() {
+      CommandStack commandStack = commandStackManager.getOrCreateCommandStack(this.participationId);
       if (commandStack != null) {
          commandStack.undo();
       }
@@ -112,6 +113,7 @@ public void undo() {
 
    @Override
    public void redo() {
+      CommandStack commandStack = commandStackManager.getOrCreateCommandStack(this.participationId);
       if (commandStack != null) {
          commandStack.redo();
       }
@@ -119,11 +121,13 @@ public void redo() {
 
    @Override
    public boolean isDirty() {
+      CommandStack commandStack = commandStackManager.getOrCreateCommandStack(this.participationId);
       return commandStack instanceof BasicCommandStack && ((BasicCommandStack) commandStack).isSaveNeeded();
    }
 
    @Override
    public void saveIsDone() {
+      CommandStack commandStack = commandStackManager.getOrCreateCommandStack(this.participationId);
       if (commandStack instanceof BasicCommandStack) {
          ((BasicCommandStack) commandStack).saveIsDone();
       }
@@ -150,4 +154,10 @@ public <P> Optional<P> getProperty(final String key, final Class<P> type) {
    public void clearProperty(final String key) {
       properties.remove(key);
    }
+
+   @Override
+   public void setParticipationID(final String id) {
+      this.participationId = id;
+
+   }
 }
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/model/GModelState.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/model/GModelState.java
index e9ea274d..c147ba73 100644
--- a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/model/GModelState.java
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/model/GModelState.java
@@ -44,4 +44,6 @@ public interface GModelState extends ModelState<GModelRoot> {
     * @param command The {@link Command} to be executed.
     */
    void execute(Command command);
+
+   void setParticipationID(String id);
 }
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/utils/ClientOptionsUtil.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/utils/ClientOptionsUtil.java
index afe28b25..586ce836 100644
--- a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/utils/ClientOptionsUtil.java
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/utils/ClientOptionsUtil.java
@@ -28,6 +28,8 @@ public final class ClientOptionsUtil {
    public static final String IS_RECONNECTING = "isReconnecting";
    public static final String FILE_PREFIX = "file://";
 
+   private static final String DISABLE_RELOAD = "disableReload";
+
    private ClientOptionsUtil() {}
 
    public static Optional<String> getSourceUri(final Map<String, String> options) {
@@ -38,6 +40,15 @@ public static Optional<String> getDiagramType(final Map<String, String> options)
       return MapUtil.getValue(options, DIAGRAM_TYPE);
    }
 
+   public static Optional<Boolean> getDisableReload(final Map<String, String> options) {
+      return MapUtil.getValue(options, DISABLE_RELOAD).map(Boolean::valueOf);
+   }
+
+   public static Boolean disableReloadIsTrue(final Map<String, String> options) {
+      Optional<Boolean> disableReload = getDisableReload(options);
+      return disableReload.isPresent() && disableReload.get();
+   }
+
    public static Optional<File> getSourceUriAsFile(final Map<String, String> options) {
       return MapUtil.getValue(options, SOURCE_URI).map(ClientOptionsUtil::getAsFile);
    }
diff --git a/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/utils/CollaborationUtil.java b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/utils/CollaborationUtil.java
new file mode 100644
index 00000000..82989403
--- /dev/null
+++ b/plugins/org.eclipse.glsp.server/src/org/eclipse/glsp/server/utils/CollaborationUtil.java
@@ -0,0 +1,21 @@
+/********************************************************************************
+ * Copyright (c) 2020 EclipseSource and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * https://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the Eclipse
+ * Public License v. 2.0 are satisfied: GNU General Public License, version 2
+ * with the GNU Classpath Exception which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ ********************************************************************************/
+
+package org.eclipse.glsp.server.utils;
+
+public class CollaborationUtil {
+    public static final String FALLBACK_SUBCLIENT_ID = "FALLBACK_SUBCLIENT_ID";
+}