Unusual issue posting a check to a customer's invoice
Hello, we own a horse training business and we sold a horse for one of our customers. The buyer wrote the check for payment to our business and the check was deposited to our business checking account. Part of the check needs to be applied to the customer's outstanding invoices and the remaining amount returned to the customer. How can I apply a payment to an invoice which was not received by the customer whose name is on the invoice, and how can I post only part of the check to invoice payments, and the rest due to the customer? Any insight on this would be appreciated!

