Hey there! Thanks for the response.
Are you trying to get this to line up with an accounting system? Sounds like what you want is to have a single PO, then on that one PO show what was received on each shipment and the associated invoice number.
I'd be interested in digging into this more with you if you have like 10 minutes for a quick call. Do you want to shoot me an email? firstname.lastname@example.org
Not necessarily for lining up with accounting programs. But it is rare that a shipper sends the items on a purchase order perfect. They sometimes overship an item, send multiple shipments for a purchase order, short ship, etc. So the only thing we can do is clone the PO - take off the items that have been received - put in notes somewhere that this is a back order of specific PO number. And then you have to go into the PO that you received partial - and delete those items so your invoice will match up.
My email is email@example.com