diff --git a/odk/odk.py b/odk/odk.py
index 261f48f9..3aeb5fbf 100755
--- a/odk/odk.py
+++ b/odk/odk.py
@@ -318,6 +318,12 @@ class ImportGroup(ProductGroup):
     
     directory : Directory = "imports/"
     """directory where imports are extracted into to"""
+    
+    annotate_defined_by : bool = False
+    """If set to true, the annotation rdfs:definedBy is added for each external class. 
+       In the case of use_base_merging is also true, this will be added to the imports/merged_import.owl file.
+       When imports are not merged, the annotation is added during the release process to the full release artefact.
+    """
 
     def _add_stub(self, id : OntologyHandle):
         if self.products is None:
diff --git a/template/src/ontology/Makefile.jinja2 b/template/src/ontology/Makefile.jinja2
index d990caa8..6a47873e 100644
--- a/template/src/ontology/Makefile.jinja2
+++ b/template/src/ontology/Makefile.jinja2
@@ -634,7 +634,7 @@ ALL_MIRRORS = $(patsubst %, $(MIRRORDIR)/%.owl, $(IMPORTS))
 MERGE_MIRRORS = true
 
 $(MIRRORDIR)/merged.owl: $(ALL_MIRRORS)
-	if [ $(IMP) = true ] && [ $(MERGE_MIRRORS) = true ]; then $(ROBOT) merge $(patsubst %, -i %, $^) {% if project.import_group.base_merge_drop_equivalent_class_axioms %}remove --axioms equivalent --preserve-structure false {% endif %}-o $@; fi
+	if [ $(IMP) = true ] && [ $(MERGE_MIRRORS) = true ]; then $(ROBOT) merge $(patsubst %, -i %, $^) {% if project.import_group.annotate_defined_by %}--annotate-defined-by true{% endif %} {% if project.import_group.base_merge_drop_equivalent_class_axioms %}remove --axioms equivalent --preserve-structure false {% endif %}-o $@; fi
 .PRECIOUS: $(MIRRORDIR)/merged.owl
 {% endif %}
 
@@ -915,7 +915,7 @@ $(ONT).owl: $(ONT)-{{ project.primary_release }}.owl
 {% endif -%}
 
 # ROBOT pipeline that merges imports, including components.
-ROBOT_RELEASE_IMPORT_MODE={% if project.use_edit_file_imports -%}$(ROBOT) merge --input $< {% else -%}
+ROBOT_RELEASE_IMPORT_MODE={% if project.use_edit_file_imports -%}$(ROBOT) merge --input $< {% if project.import_group is defined and project.import_group.use_base_merging is false and project.import_group.annotate_defined_by %}--annotate-defined-by true{% endif -%}{% else -%}
 $(ROBOT) remove --input $< --select imports --trim false {% if project.use_dosdps or project.components is defined -%}
 merge $(patsubst %, -i %, $(OTHER_SRC)) {% endif %}{% if project.import_group is defined -%}
 merge $(patsubst %, -i %, $(IMPORT_FILES)){% endif %}{% endif %}