diff --git a/src/ifcopenshell-python/ifcopenshell/api/classification/add_reference.py b/src/ifcopenshell-python/ifcopenshell/api/classification/add_reference.py
index b6d3f6deba..bd73c4b39d 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/classification/add_reference.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/classification/add_reference.py
@@ -42,7 +42,7 @@ class Usecase:
     def add_from_identification(self):
         reference = self.get_existing_reference(self.settings["identification"])
         if reference:
-            self.add_to_existing_relationship()
+            self.add_to_existing_relationship(reference)
         else:
             reference = self.file.createIfcClassificationReference(
                 Name=self.settings["name"], ReferencedSource=self.settings["classification"]
@@ -63,7 +63,7 @@ class Usecase:
         reference = self.get_existing_reference(identification)
 
         if reference:
-            self.add_to_existing_relationship()
+            self.add_to_existing_relationship(reference)
             return reference
 
         migrator = ifcopenshell.util.schema.Migrator()
diff --git a/src/ifcopenshell-python/ifcopenshell/api/classification/remove_reference.py b/src/ifcopenshell-python/ifcopenshell/api/classification/remove_reference.py
index 860ad34383..86f2995938 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/classification/remove_reference.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/classification/remove_reference.py
@@ -16,8 +16,6 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 
-import ifcopenshell.util.schema
-
 
 class Usecase:
     def __init__(self, file, **settings):
diff --git a/src/ifcopenshell-python/test/api/classification/test_add_classification_reference.py b/src/ifcopenshell-python/test/api/classification/test_add_classification_reference.py
index 50a4d9ec66..c357811e27 100644
--- a/src/ifcopenshell-python/test/api/classification/test_add_classification_reference.py
+++ b/src/ifcopenshell-python/test/api/classification/test_add_classification_reference.py
@@ -40,6 +40,19 @@ class TestAddReference(test.bootstrap.IFC4):
         assert references[0].Name == "Foobar"
         assert references[0].ReferencedSource == self.file.by_type("IfcClassification")[0]
 
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run(
+            "classification.add_reference",
+            self.file,
+            product=element2,
+            identification="X",
+            name="Foobar",
+            classification=result,
+        )
+        assert list(ifcopenshell.util.classification.get_references(element2))[0].Identification == "X"
+        assert list(ifcopenshell.util.classification.get_references(element2))[0].Name == "Foobar"
+        assert list(ifcopenshell.util.classification.get_references(element2))[0] == references[0]
+
     def test_adding_a_reference_from_a_library(self):
         library = ifcopenshell.file()
         classification = library.createIfcClassification(Name="Name")
diff --git a/src/ifcopenshell-python/test/util/test_pset.py b/src/ifcopenshell-python/test/util/test_pset.py
index 61331d2724..9fefd61396 100644
--- a/src/ifcopenshell-python/test/util/test_pset.py
+++ b/src/ifcopenshell-python/test/util/test_pset.py
@@ -36,15 +36,15 @@ class TestPsetQto:
 
     def test_getting_applicables_for_a_specific_predefined_type(self):
         names = self.pset_qto.get_applicable_names("IfcAudioVisualAppliance")
-        assert len(names) == 17
+        assert len(names) == 12
         assert "Pset_AudioVisualApplianceTypeAmplifier" not in names
         names = self.pset_qto.get_applicable_names("IfcAudioVisualAppliance", predefined_type="AMPLIFIER")
         assert "Pset_AudioVisualApplianceTypeAmplifier" in names
-        assert len(names) == 18
+        assert len(names) == 13
 
     def test_getting_a_pset_of_a_type_where_the_type_class_is_not_explicitly_applicable(self):
         names = self.pset_qto.get_applicable_names("IfcWall")
         assert "Pset_WallCommon" in names
         names = self.pset_qto.get_applicable_names("IfcWallType")
-        assert len(names) == 9
+        assert len(names) == 5
         assert "Pset_WallCommon" in names
diff --git a/src/ifcpatch/ifcpatch/recipes/MergeDuplicateTypesByTag.py b/src/ifcpatch/ifcpatch/recipes/MergeDuplicateTypesByTag.py
index eec13aecc9..345ff5bbce 100644
--- a/src/ifcpatch/ifcpatch/recipes/MergeDuplicateTypesByTag.py
+++ b/src/ifcpatch/ifcpatch/recipes/MergeDuplicateTypesByTag.py
@@ -1,6 +1,5 @@
-
 # IfcPatch - IFC patching utiliy
-# Copyright (C) 2020, 2021 Dion Moult <dion@thinkmoult.com>
+# Copyright (C) 2020-2022 Dion Moult <dion@thinkmoult.com>
 #
 # This file is part of IfcPatch.
 #
@@ -30,11 +29,59 @@ class Patcher:
 
     def patch(self):
         tags = {}
-        for element in self.file.by_type("IfcTypeObject"):
-            original_element = tags.get(element.Tag, None)
-            if original_element:
-                for inverse in self.file.get_inverse(element):
-                    ifcopenshell.util.element.replace_attribute(inverse, element, original_element)
-                self.file.remove(element)
+        for element_type in self.file.by_type("IfcTypeObject"):
+            original_type = tags.get(element_type.Tag, None)
+            if original_type:
+                for element in ifcopenshell.util.element.get_types(element_type):
+                    self.assign_type(element, original_type)
+                for inverse in self.file.get_inverse(element_type):
+                    ifcopenshell.util.element.replace_attribute(inverse, element_type, original_type)
+                self.file.remove(element_type)
             else:
-                tags[element.Tag] = element
+                tags[element_type.Tag] = element_type
+
+    def assign_type(self, related_object, relating_type):
+        # This is basically a portion of the type.assign_type API which only
+        # affects the IfcRelDefinesByType relationship. To be conservative, we
+        # don't use the API directly since that would do other things like
+        # map type representations or recalculate material set usages which is
+        # risky when we're patching an existing dataset.
+        if self.file.schema == "IFC2X3":
+            is_typed_by = None
+            is_defined_by = related_object.IsDefinedBy
+            for rel in is_defined_by:
+                if rel.is_a("IfcRelDefinesByType"):
+                    is_typed_by = [rel]
+                    break
+            types = relating_type.ObjectTypeOf
+        else:
+            is_typed_by = related_object.IsTypedBy
+            types = relating_type.Types
+
+        if types and is_typed_by == types:
+            return
+
+        if is_typed_by:
+            related_objects = list(is_typed_by[0].RelatedObjects)
+            related_objects.remove(related_object)
+            if related_objects:
+                is_typed_by[0].RelatedObjects = related_objects
+                ifcopenshell.api.run("owner.update_owner_history", self.file, **{"element": is_typed_by[0]})
+            else:
+                self.file.remove(is_typed_by[0])
+
+        if types:
+            related_objects = list(types[0].RelatedObjects)
+            related_objects.append(related_object)
+            types[0].RelatedObjects = related_objects
+            ifcopenshell.api.run("owner.update_owner_history", self.file, **{"element": types[0]})
+        else:
+            types = self.file.create_entity(
+                "IfcRelDefinesByType",
+                **{
+                    "GlobalId": ifcopenshell.guid.new(),
+                    "OwnerHistory": ifcopenshell.api.run("owner.create_owner_history", self.file),
+                    "RelatedObjects": [related_object],
+                    "RelatingType": relating_type,
+                }
+            )