Don't show items in the dispacts form form if its not in ordered from the same customer

[Atlas]

Hello appsheetors.. 

Striving around for a while but didn't figure out how to bring the solution to this. I have parent-child tables, orders and order details, and dispatch and dispatch details. I want to filter the items in the dispatch form, which are not being ordered from the same customer. 

Any help appreciated.
Thanks

[Marc_Dillon · Accepted solution]

One possibility would be a valid_if, something akin to:

FILTER(
  Items ,
  ISBLANK( FILTER(
    order_details ,
    AND(
      [Customer] = [_THISROW-2].[Customer] ,
      [Item] = [_THISROW-2].[Item]
    )
  ) )
)