Dear Yaz Yamh,
In Routing we can mange the external and internal operations through Control Key i.e. PP01 (In Process) PP02 (External)
Assign the components to the first operation then make the Operation level confirmation through CO11N by activating the quality management
similarly for second operation maintain the control key as PP02 when you release the production order system will create the sub contracting PR for that particular operation
Regards,
Venkatesh..