Hi kay-bebuoyant-co, thanks for joining the Community - you can add the overpayment directly from the for-review section in your bank feed, by selecting the supplier under 'Supplier/Customer' and then the creditors (or accounts payable) under 'Category'
Or if you want to do that outside of the the banking section and there is no bill to be paid with the overpayment you can create a cheque for the amount, selecting that supplier as the payee and in the category select accounts payable/creditors and it will show as a credit amount under the supplier:)
