Serial_No is in the subform
Container_Type is actually in another subform inside the same mainform.
Both have foreign key of ShipperID.
Shipment_Table (Lists each shipment by ID and Date)
ShipperID
Shipment_Date
Material_DescriptionTBL (Lists number of containers and Container on each shipment)
Truck_Number
Trailer_Number
Material_Type
No_of_containers
Container_Type
Container_TBL (This table lists all the containers by serial number and Container Type)
Serial_Number
Container_Type
TrackPacages_TBL (Table lists which containers are on which truck and shipment)
ShipperID
Serial_No (This is the field for which I need the filtered drop-down. Essentially we have about 1500 containers and my thinking is that if I can filter it by container type, then our drop-down items would be significantly reduced)