I have a form with a subform, the user creates a parts trace list by selecting a pipe size. I have the pipe size in a dropdown field on the form, in the subform is where the person puts in a serial number given to them by a field worker. That serial number ties to a Part number and pipe size. I am trying to make only the serial numbers/part numbers that match the selected pipe size available in the subform list and if they enter a SN that does not relate to that pipe size they will get the message that the part number does not exist in the list.

I used a query to do this and it worked when I pre-filtered the query to match the pipe size. How can I make the query list update when a pipe size on the parent form is changed and before a SN is selected on the subform?