Yes, build a structure for the subcontracted material that includes two parts - the raw material they send for subcontracting and a new item for the labor portion. Create the PO using the labor part (that's what they're generally buying is labor) and transfer the raw material to the Vendor Whse. When the part comes in, receive the PO and run a Production Entry which will clear the item out of the Vendor's warehouse and the Labor part in stock. And voila...finished subcontracted part in stock.