PO Receiving - Back Order quantity

Can someone suggest how to record back ordered quantity while doing standard receipt?

Say, for e.g. 100 quantities on a pallet is at 'Receiving' . Now opened the pallet for 'Delivery' and found that 5 quantities are missing (or back ordered).

How can we keep the Purchase Order updated in such a way that Received Qty on the PO is 95, while using standard receipt? What I found is that since all 100 are in 'Receiving' , Purchase Order shows 100 as received quantity. I want it to show only 95 since 5 has been missing/backordered.

Thanks,