I'd be glad to assist you with processing an order for a customer.
For the best resolution, I'd recommend reaching out to your accountant.
I'm unable to advise you on which route would be best for your business, but you can do a Sales Order which is used to record a sale that you plan to fulfill in the future, and when the product returns you can create an Invoice which is a bill for your customer.
Click on the Sales Orders icon on the home page.
Select Create Sales Orders.
Create an invoice for a Sales Order
From the Sales Order window, select the Create Invoice button.
On the prompt that appears, choose:
Choose to Create an invoice for all of the sales order(s) to add all items from the sales order to the invoice.
Click Create an invoice for selected items if you want to put only some of the items on the invoice.