If I add new items to stock directly by creating new receipts (before creating a Purchase Order), I'm unable to automatically generate a Purchase Order with all the items that have been marked with same Source Document e.g. PO00001. Is there a default way to generate the PO once I have all items added to stock (individually, by creating seperate receipts) from the same Source Document PO00001?

Or is this something I will have to develop a module to automatically generate a PO and a Bill, so we wouldn't have to add items manually?

This is a weird business flow, but at input we don't process all received items as soon as we get them and rather process them individually and from several different sources at the same time during a span of ~1week, but we need to add processed items to stock as soon as we check the quality..