How can we improve WHMCS?

There some time that needs to move some paid invoices from one client to another. I would love that I can just simply alter the client on the invoice I want to change. Maybe when I click the Invice> Options I can see a Click that I get to choose a different client, and after I alter it to another client, the system will also move data to the new client. It will be more convenient than deleting the original invoice and create the same invoice but a different client one by one manually.
It will be very helpful, thanks