diff --git a/src/blenderbim/blenderbim/bim/helper.py b/src/blenderbim/blenderbim/bim/helper.py
index e445aa67fb..3b255f76e7 100644
--- a/src/blenderbim/blenderbim/bim/helper.py
+++ b/src/blenderbim/blenderbim/bim/helper.py
@@ -18,7 +18,7 @@ def import_attributes(ifc_class, props, data, callback=None):
         new.is_null = data[attribute.name()] is None
         new.is_optional = attribute.optional()
         new.data_type = data_type if isinstance(data_type, str) else ""
-        is_handled_by_callback = callback(attribute.name(), new, data) if callback else False
+        is_handled_by_callback = callback(attribute.name(), new, data) if callback else None
         if is_handled_by_callback:
             pass  # Our job is done
         elif is_handled_by_callback is False:
diff --git a/src/blenderbim/blenderbim/bim/module/cost/__init__.py b/src/blenderbim/blenderbim/bim/module/cost/__init__.py
index 242c41809b..2368b1b783 100644
--- a/src/blenderbim/blenderbim/bim/module/cost/__init__.py
+++ b/src/blenderbim/blenderbim/bim/module/cost/__init__.py
@@ -24,8 +24,8 @@ classes = (
     operator.ExpandCostItem,
     operator.ContractCostItem,
     operator.RemoveCostItem,
-    operator.AssignControl,
-    operator.UnassignControl,
+    operator.AssignCostItemProduct,
+    operator.UnassignCostItemProduct,
     operator.AddCostItemQuantity,
     operator.RemoveCostItemQuantity,
     operator.AddCostValue,
diff --git a/src/blenderbim/blenderbim/bim/module/cost/operator.py b/src/blenderbim/blenderbim/bim/module/cost/operator.py
index 134fdb757a..9348d4d90e 100644
--- a/src/blenderbim/blenderbim/bim/module/cost/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/cost/operator.py
@@ -3,6 +3,7 @@ import bpy
 import json
 import ifcopenshell.api
 import blenderbim.bim.helper
+from blenderbim.bim.module.cost.prop import purge
 from blenderbim.bim.ifc import IfcStore
 from ifcopenshell.api.cost.data import Data
 
@@ -259,8 +260,8 @@ class EditCostItem(bpy.types.Operator):
         return {"FINISHED"}
 
 
-class AssignControl(bpy.types.Operator):
-    bl_idname = "bim.assign_control"
+class AssignCostItemProduct(bpy.types.Operator):
+    bl_idname = "bim.assign_cost_item_product"
     bl_label = "Assign Control"
     cost_item: bpy.props.IntProperty()
     related_object: bpy.props.StringProperty()
@@ -269,20 +270,23 @@ class AssignControl(bpy.types.Operator):
         related_objects = (
             [bpy.data.objects.get(self.related_object)] if self.related_object else bpy.context.selected_objects
         )
-        for related_object in related_objects:
-            self.file = IfcStore.get_file()
-            ifcopenshell.api.run(
-                "control.assign_control",
-                self.file,
-                related_object=self.file.by_id(related_object.BIMObjectProperties.ifc_definition_id),
-                relating_control=self.file.by_id(self.cost_item),
-            )
+        self.file = IfcStore.get_file()
+        ifcopenshell.api.run(
+            "cost.assign_cost_item_product",
+            self.file,
+            cost_item=self.file.by_id(self.cost_item),
+            products=[
+                self.file.by_id(o.BIMObjectProperties.ifc_definition_id)
+                for o in related_objects
+                if o.BIMObjectProperties.ifc_definition_id
+            ],
+        )
         Data.load(self.file)
         return {"FINISHED"}
 
 
-class UnassignControl(bpy.types.Operator):
-    bl_idname = "bim.unassign_control"
+class UnassignCostItemProduct(bpy.types.Operator):
+    bl_idname = "bim.unassign_cost_item_product"
     bl_label = "Unassign Control"
     cost_item: bpy.props.IntProperty()
     related_object: bpy.props.StringProperty()
@@ -291,14 +295,17 @@ class UnassignControl(bpy.types.Operator):
         related_objects = (
             [bpy.data.objects.get(self.related_object)] if self.related_object else bpy.context.selected_objects
         )
-        for related_object in related_objects:
-            self.file = IfcStore.get_file()
-            ifcopenshell.api.run(
-                "control.unassign_control",
-                self.file,
-                related_object=self.file.by_id(related_object.BIMObjectProperties.ifc_definition_id),
-                relating_control=self.file.by_id(self.cost_item),
-            )
+        self.file = IfcStore.get_file()
+        ifcopenshell.api.run(
+            "cost.unassign_cost_item_product",
+            self.file,
+            cost_item=self.file.by_id(self.cost_item),
+            products=[
+                self.file.by_id(o.BIMObjectProperties.ifc_definition_id)
+                for o in related_objects
+                if o.BIMObjectProperties.ifc_definition_id
+            ],
+        )
         Data.load(self.file)
         return {"FINISHED"}
 
@@ -312,6 +319,7 @@ class EnableEditingCostItemQuantities(bpy.types.Operator):
         props = context.scene.BIMCostProperties
         props.active_cost_item_id = self.cost_item
         props.cost_item_editing_type = "QUANTITIES"
+        purge()
         return {"FINISHED"}
 
 
@@ -348,8 +356,7 @@ class AddCostItemQuantity(bpy.types.Operator):
             "cost.assign_cost_item_product_quantities",
             self.file,
             cost_item=self.file.by_id(self.cost_item),
-            qto_name=self.props.qto_name,
-            prop_name=self.props.prop_name
+            prop_name=self.props.quantity_names,
         )
 
     def add_manual_quantity(self):
@@ -439,9 +446,7 @@ class AddCostValue(bpy.types.Operator):
         elif self.cost_type == "CATEGORY":
             category = self.cost_category
         value = ifcopenshell.api.run("cost.add_cost_value", self.file, parent=self.file.by_id(self.parent))
-        ifcopenshell.api.run(
-            "cost.edit_cost_value", self.file, cost_value=value, attributes={"Category": category}
-        )
+        ifcopenshell.api.run("cost.edit_cost_value", self.file, cost_value=value, attributes={"Category": category})
         Data.load(self.file)
         return {"FINISHED"}
 
diff --git a/src/blenderbim/blenderbim/bim/module/cost/prop.py b/src/blenderbim/blenderbim/bim/module/cost/prop.py
index 3ee77dd403..16c48c736c 100644
--- a/src/blenderbim/blenderbim/bim/module/cost/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/cost/prop.py
@@ -2,6 +2,7 @@ import bpy
 import ifcopenshell.api
 from blenderbim.bim.ifc import IfcStore
 from ifcopenshell.api.cost.data import Data
+from ifcopenshell.api.pset.data import Data as PsetData
 from blenderbim.bim.prop import StrProperty, Attribute
 from bpy.types import PropertyGroup
 from bpy.props import (
@@ -17,17 +18,19 @@ from bpy.props import (
 
 
 quantitytypes_enum = []
+quantitynames_enum = []
 
 
 def purge():
     global quantitytypes_enum
+    global quantitynames_enum
     quantitytypes_enum = []
+    quantitynames_enum = []
 
 
 def getQuantityTypes(self, context):
     global quantitytypes_enum
     if len(quantitytypes_enum) == 0 and IfcStore.get_schema():
-        quantitytypes_enum.clear()
         quantitytypes_enum = [("QTO", "Qto", "Derive quantities from IFC quantity sets")]
         quantitytypes_enum.extend(
             [
@@ -38,6 +41,21 @@ def getQuantityTypes(self, context):
     return quantitytypes_enum
 
 
+def getQuantityNames(self, context):
+    global quantitynames_enum
+    ifc_file = IfcStore.get_file()
+    if len(quantitynames_enum) == 0 and ifc_file:
+        names = set()
+        for element_id in Data.cost_items[self.active_cost_item_id]["Controls"]:
+            if element_id not in PsetData.products:
+                PsetData.load(IfcStore.get_file(), element_id)
+            for qto_id in PsetData.products[element_id]["qtos"]:
+                qto = PsetData.qtos[qto_id]
+                [names.add(PsetData.properties[p]["Name"]) for p in qto["Properties"]]
+        quantitynames_enum.extend([(n, n, "") for n in names])
+    return quantitynames_enum
+
+
 def updateCostItemName(self, context):
     if self.name == "Unnamed":
         return
@@ -73,8 +91,7 @@ class BIMCostProperties(PropertyGroup):
     cost_item_attributes: CollectionProperty(name="Task Attributes", type=Attribute)
     contracted_cost_items: StringProperty(name="Contracted Cost Items", default="[]")
     quantity_types: EnumProperty(items=getQuantityTypes, name="Quantity Types")
-    qto_name: StringProperty(name="Qto Name")
-    prop_name: StringProperty(name="Prop Name")
+    quantity_names: EnumProperty(items=getQuantityNames, name="Quantity Names")
     active_cost_item_quantity_id: IntProperty(name="Active Cost Item Quantity Id")
     quantity_attributes: CollectionProperty(name="Quantity Attributes", type=Attribute)
     cost_types: EnumProperty(
diff --git a/src/blenderbim/blenderbim/bim/module/cost/ui.py b/src/blenderbim/blenderbim/bim/module/cost/ui.py
index 30ecd8f07f..e02226edfa 100644
--- a/src/blenderbim/blenderbim/bim/module/cost/ui.py
+++ b/src/blenderbim/blenderbim/bim/module/cost/ui.py
@@ -97,8 +97,7 @@ class BIM_PT_cost_schedules(Panel):
         row = self.layout.row(align=True)
         row.prop(self.props, "quantity_types", text="")
         if self.props.quantity_types == "QTO":
-            row.prop(self.props, "qto_name", text="")
-            row.prop(self.props, "prop_name", text="")
+            row.prop(self.props, "quantity_names", text="")
         op = row.operator("bim.add_cost_item_quantity", text="", icon="ADD")
         op.cost_item = self.props.active_cost_item_id
         op.ifc_class = self.props.quantity_types
@@ -254,10 +253,10 @@ class BIM_UL_cost_items(UIList):
                 oprops = context.active_object.BIMObjectProperties
                 row = layout.row(align=True)
                 if oprops.ifc_definition_id in cost_item["Controls"]:
-                    op = row.operator("bim.unassign_control", text="", icon="KEYFRAME_HLT", emboss=False)
+                    op = row.operator("bim.unassign_cost_item_product", text="", icon="KEYFRAME_HLT", emboss=False)
                     op.cost_item = item.ifc_definition_id
                 else:
-                    op = row.operator("bim.assign_control", text="", icon="KEYFRAME", emboss=False)
+                    op = row.operator("bim.assign_cost_item_product", text="", icon="KEYFRAME", emboss=False)
                     op.cost_item = item.ifc_definition_id
 
             if props.active_cost_item_id == item.ifc_definition_id:
diff --git a/src/ifcopenshell-python/ifcopenshell/api/cost/assign_cost_item_product.py b/src/ifcopenshell-python/ifcopenshell/api/cost/assign_cost_item_product.py
new file mode 100644
index 0000000000..df0944a876
--- /dev/null
+++ b/src/ifcopenshell-python/ifcopenshell/api/cost/assign_cost_item_product.py
@@ -0,0 +1,31 @@
+import ifcopenshell.api
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"cost_item": None, "products": []}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        quantity_names = set()
+        for quantity in self.settings["cost_item"].CostQuantities or []:
+            if quantity.Name:
+                quantity_names.add(quantity.Name)
+
+        for product in self.settings["products"]:
+            ifcopenshell.api.run(
+                "control.assign_control",
+                self.file,
+                related_object=product,
+                relating_control=self.settings["cost_item"],
+            )
+
+        for name in quantity_names:
+            ifcopenshell.api.run(
+                "cost.assign_cost_item_product_quantities",
+                self.file,
+                cost_item=self.settings["cost_item"],
+                prop_name=name
+            )
diff --git a/src/ifcopenshell-python/ifcopenshell/api/cost/assign_cost_item_product_quantities.py b/src/ifcopenshell-python/ifcopenshell/api/cost/assign_cost_item_product_quantities.py
index c20a2fa861..eea39bf633 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/cost/assign_cost_item_product_quantities.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/cost/assign_cost_item_product_quantities.py
@@ -4,7 +4,7 @@ import ifcopenshell.api
 class Usecase:
     def __init__(self, file, **settings):
         self.file = file
-        self.settings = {"cost_item": None, "qto_name": "", "prop_name": ""}
+        self.settings = {"cost_item": None, "prop_name": ""}
         for key, value in settings.items():
             self.settings[key] = value
 
@@ -25,7 +25,7 @@ class Usecase:
                     self.add_quantity_from_qto(relationship.RelatingPropertyDefinition)
 
     def add_quantity_from_qto(self, qto):
-        if not qto.is_a("IfcElementQuantity") or qto.Name.lower() != self.settings["qto_name"].lower():
+        if not qto.is_a("IfcElementQuantity"):
             return
         for prop in qto.Quantities:
             if prop.is_a("IfcPhysicalSimpleQuantity") and prop.Name.lower() == self.settings["prop_name"].lower():
diff --git a/src/ifcopenshell-python/ifcopenshell/api/cost/unassign_cost_item_product.py b/src/ifcopenshell-python/ifcopenshell/api/cost/unassign_cost_item_product.py
new file mode 100644
index 0000000000..ec652a0e10
--- /dev/null
+++ b/src/ifcopenshell-python/ifcopenshell/api/cost/unassign_cost_item_product.py
@@ -0,0 +1,29 @@
+import ifcopenshell.api
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"cost_item": None, "products": []}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        self.quantities = set(self.settings["cost_item"].CostQuantities or [])
+        for quantity in self.settings["cost_item"].CostQuantities or []:
+            for inverse in self.file.get_inverse(quantity):
+                if not inverse.is_a("IfcElementQuantity"):
+                    continue
+                for rel in inverse.DefinesOccurrence or []:
+                    for related_object in rel.RelatedObjects:
+                        if related_object in self.settings["products"]:
+                            self.quantities.remove(quantity)
+        self.settings["cost_item"].CostQuantities = list(self.quantities)
+
+        for product in self.settings["products"]:
+            ifcopenshell.api.run(
+                "control.unassign_control",
+                self.file,
+                related_object=product,
+                relating_control=self.settings["cost_item"],
+            )