Accounts payable posted against a receivable

SUGGESTED

Hi all - got a bit of a strange dilemma here...

We have a customer that owes us some money (say, $10,000) and they have been very late to pay us. We also owe this customer money ($12,000.00), so my boss has requested we send a cheque for the difference of $2,000 to them, therefore taking care of both the receiveable and payable aspect.

Makes sense, but how on earth do I post this?

Thank you for any suggestions!