Error referencing contract principal purchase agreement number in purchase order

Dear,

I'm adding a BOM item into stock transport order. Im getting an error when saving stock transport order " when referencing a contract, please enter a contract item number"

This is because EKPO-KONNR field is populated but the item field EKPO-KTPNR is not.  Program is set to clear out this field when sto creates but Agreement (and higher level item) still populate anyway even though we tell the BAPI not to. Do you know if there is configuration to make the agreement field not relevant for the sto?

Thanks.