Supplier number in outside operations

I have a manufactured item which is attached to a master routing. This master routing is used for multiple items, which has outside operations associated with it.

The routing is having a supplier number which is picked to create a purchase order.

now user wants the supplier number to be different for two items - which means i will not able to change the supplier number in routing as its a master routing and it will impact other items.

Is there a way to make JDE to pick different supplier number only for those specific items.

Note: i tried giving supplier number for *OP item in item branch but the PO is still getting created with master routing supplier number