Advanced Sale Invoicing & Receiving advice?

We often find ourselves in this situation and are looking for advice. Most of our purchases are invoiced after being shipped. So our warehouse team check the stock in and the invoice is added later by accounts. However, in an advanced sale, each Invoicing & Receiving line must all tally up. So if you received x10 the invoice needs to have x10 on it. However, for example(and to keep it simple), we often receive x10 however the supplier sends two invoices for x5 + x5. BUT you cannot add more than one invoice to an I&R line. We cannot undo the receiving as the stock is already sold. So our only option is to not use the invoice on the line with the receive, then create two new I&R lines for each invoice. This then creates problems. These additional lines show up as waiting for stock. The first line is flagged as not invoiced. AND the item costs for cogs /margin etc is not pulled through. 

Any advice is appreciated.