1.
Make an order for the customer.
Make it have no balance due – the order total equals zero.
2.
Put an X item in the order saying what the order is for, e.g. this
order reflects a payment to this customer to use up their credit balance from
… This
X item should not add any amount to the already zero order total.
3.
Enter a negative payment for the
amount you want to pay them. A negative
payment is equivalent to saying that you are paying them instead of the normal
positive payment which is them paying you.
4.
Finalize/post the invoice.
5.
Use AR to apply the prior existing credit to the invoice created above.
All
done.