Generating a Debit Memo from Return to Supplier when no invoice has been matched.

We have a requirement to generate a debit memo from a return to supplier transaction even when an invoice has not been matched.  This is to enable handling of returns which are usually identified at time of receipt. The industry is Glass Manufacture.  Defective raw glass is not physically returned - it is scrapped on receipt.  But to manage the request for credit, an automatically created debit memo would be a good solution.  Due to the timing of the return , the inovice is rarely matched to the PO.  As an example - if 10 sheets of glass are ordered and on receipt