diff --git a/src/blenderbim/blenderbim/core/tool.py b/src/blenderbim/blenderbim/core/tool.py
index 261029e27f..41f9df6b8c 100644
--- a/src/blenderbim/blenderbim/core/tool.py
+++ b/src/blenderbim/blenderbim/core/tool.py
@@ -65,10 +65,12 @@ class Demo:
 
 @interface
 class Aggregate:
-    def can_aggregate(cls, relating_object, related_object): pass
+    def can_aggregate(cls, relating_obj, related_obj): pass
+    def has_physical_body_representation(cls, element): pass
     def disable_editing(cls, obj): pass
     def enable_editing(cls, obj): pass
     def get_container(cls, element): pass
+    def get_relating_object(cls, related_element): pass
 
 
 @interface
diff --git a/src/blenderbim/test/core/test_aggregate.py b/src/blenderbim/test/core/test_aggregate.py
index e4f3efe58d..81e967de94 100644
--- a/src/blenderbim/test/core/test_aggregate.py
+++ b/src/blenderbim/test/core/test_aggregate.py
@@ -36,6 +36,7 @@ class TestAssignObject:
     def test_run(self, ifc, aggregate, collector):
         aggregate.can_aggregate("relating_obj", "related_obj").should_be_called().will_return(True)
         ifc.get_entity("relating_obj").should_be_called().will_return("relating_object")
+        aggregate.has_physical_body_representation("relating_object").should_be_called().will_return(False)
         ifc.get_entity("related_obj").should_be_called().will_return("related_object")
         ifc.run(
             "aggregate.assign_object", products=["related_object"], relating_object="relating_object"