How to apply a Credit Memo to a payables invoice

Hi,

I have an invoice and credit memo lying open for a vendor for quite a long time, and now i want to close both of them.

I don't want to use a zero payment, to close both of them, becuase it will consume one  check number. And if i tried to create a payment with dummy payment document, for the same payment method, in the payments window i can't see both invoice and Credit Note. Hence i don't want to use a dummy payment to close invoice and CN

Is there any way i can apply this Credit memo to invoice?