Serial Number for purchase receipt of subcontracted serialized item

We have a raw material (item1) which is a serialized item. It is issued to the subcontractor to manufacture another item(item2) which is also serialized. We issued an purchase order and transferred item1 to the subcontractor and have mentioned serial numbers in the stock entry.
When we are creating a purchase receipt, against the same purchase order, we have put the serial number for item2. However when we are submitting the purchase receipt, erp is asking for the serial number for item1. How do we enter that serial number? Should it not take the serial number from the stock entry?




Serial No is linked to Item.

I suggest you receive Item1 and then make a repack entry to Item2