You can return multiple items from one transaction at separate times.
When one item from a transaction has been returned, you can recall the same transaction to return another item by using the same process but selecting the Also Show Previously Returned function.
If the first return on the transaction has been processed and the customer wishes to return another item, simply select Return Transactions from the Quick Action buttons at the bottom of the screen:
At the next step select Search Transactions:
This will show the transactions list and you will notice the transaction you are looking for is missing:
Select the checkbox at the top of this screen marked Also Show Previously Returned:
Then click Apply under Apply Filter:
This will then show all of the transactions. You can select the transaction required and return the required item/s: