diff --git a/NAMESPACE b/NAMESPACE
index b80da52d..3bbf6aaa 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -25,6 +25,7 @@ export(createExecuteSettings)
 export(createExistingSplitSettings)
 export(createFeatureEngineeringSettings)
 export(createGlmModel)
+export(createIterativeImputer)
 export(createLearningCurve)
 export(createLogSettings)
 export(createModelDesign)
@@ -35,7 +36,6 @@ export(createRandomForestFeatureSelection)
 export(createRareFeatureRemover)
 export(createRestrictPlpDataSettings)
 export(createSampleSettings)
-export(createSingleImputer)
 export(createSklearnImputer)
 export(createSplineSettings)
 export(createStratifiedImputationSettings)
diff --git a/R/PreprocessingData.R b/R/PreprocessingData.R
index bd065ae4..fba55fc3 100644
--- a/R/PreprocessingData.R
+++ b/R/PreprocessingData.R
@@ -151,10 +151,9 @@ minMaxNormalize <- function(trainData, featureEngineeringSettings, normalized =
     )
   )
 
-  attr(trainData, "metaData")$featureEngineering <- listAppend(
-    attr(trainData, "metaData")$featureEngineering,
+  attr(trainData, "metaData")$featureEngineering[["minMaxNormalize"]] ->
     featureEngineering
-  )
+  
   return(trainData)
 }
 
@@ -240,10 +239,8 @@ robustNormalize <- function(trainData, featureEngineeringSettings, normalized =
     )
   )
 
-  attr(trainData, "metaData")$featureEngineering <- listAppend(
-    attr(trainData, "metaData")$featureEngineering,
+  attr(trainData, "metaData")$featureEngineering[['robustNormalize']] <-
     featureEngineering
-  )
   return(trainData)
 }
 
@@ -304,10 +301,8 @@ removeRareFeatures <- function(trainData, featureEngineeringSettings, findRare =
       findRare = findRare
     )
   )
-  attr(trainData, "metaData")$featureEngineering <- listAppend(
-    attr(trainData, "metaData")$featureEngineering,
+  attr(trainData, "metaData")$featureEngineering[['removeRare']] <- 
     featureEngineering
-  )
   return(trainData)
 }