Client Reimbursable Vendor Credits

Would like to be able to upload vendor receipts for credit values in the same way that you can currently upload more typical (positive number) expenses (for example, we had a fabric order where they used the wrong price but had already processed the order, so issued a follow. up credit for the discrepancy. So, for the same purchase, we have a receipt of say +$600 and a credit for -$ 250)