It often occurs that a purchase order is created for vendor A, items are received and then the invoice is sent from vendor B.

Vendor B should have been the pay-to vendor on the invoice, but it is not.

Quickest solution would be to undo the purchase receipt, change the pay-to vendor on the purchase order, re-post the receipt and then post the invoice.

However when the received items are already used or sold, that is not possible. Then another work around must be found.

It would be nice if it were possible to change the pay-to vendor on a purchase order, even after the purchase order is received.