You could issue a partial refund to a customer to allow later payment. For example, John paid in full during registration, but later request to refund partially and allow him to pay the rest of the fee next month, you can follow the steps below to issue a partial refund. 
  1. Click search box at top right
  2. Search family's last name
  3. Select appropriate family
  4. In Order History tab click desired order number
  5. In Transaction history for this order select View Transactions under appropriate payment
  6. Click Adjust payment
  7. Enter amount to be refunded
  8. Select Continue
  9. Select Submit
​​Note: Refund for the amount entered will be issued to the original method of payment and will result in a balance on the account for that order. 
1. If you would like to adjust the purchase price of a registration, please see this article on Edit Purchase Price Amount
2. If you need to create a partial refund from a credit balance, please see the steps in 
Refund Partial Amount from Credit Balance
3. If you need to credit part of your customer's payment and do not want to leave a balance in the order, please create an internal discount and apply it to the order. See below two articles: 
4. If an order was paid by credit balance, Adjust Payment is not available.