You will need to establish new material codes. If the item is to move to multiple contractors, this is trace-ability you will want.
The only other way is to add three subcontracting phases to the routing and satisfy with a purchase order and move externally through the process and receive FX off the production order upon completion. I would not recommend this as you will have no visibility of the product in the system. You do not want to issue X all three times under this scenario, merely purchase requisitions for the subcontracting labor.