Changed Net Price not getting update when PO is with reference to outline agreement

We  need to update Net price of line item by copying from line item above. Our client use to change net price with the help of Z transaction. They are changing line item net price manually by Z transaction. Data  is coming from SNC Portal and we are using BAPI_PO_CHANGE in RFC function module. They want BAPI_PO_CHANGE should copy above line item net price into new created line item net price. But, as PO is created based upon reference of outline agreement, it is picking up the agreement price. They don’t want to go for re-determining pricing conditions. Please suggest any best possible solution as I guess using Z transaction BDC to change net price is not good solution just after BAPI_PO_CHANGE.

Thanks,

Praveen