@HAYLEY.WILLIAMS,
A- Has the last delivery made to address 1 partially consumed by the customer? If not, you can return the CO delivery by Undo Customer Order Delivery
B- If you want to return using RMA, you will need to Consume the pending stock, return and send again to the correct delivery address. (you can return the partial qty which was remaining and create a credit invoice for that amount)
C- If you are anyways going to invoice the customer for the old delivery address (because this was used in the CO), you can consume from the old delivery address without trying to do any changes.
Anyhow, I believe it would be more convenient to have a functionality to change the addresses of consignment stock in situations like yours. I dont see any functionality in the current design, which I might raise as a new idea in IFS Community.