To make it simple, we made a mistake and made the wrong invoice... that number was supposed to go to another.
We deleted the invoice, but now when we make a new one instead of being #64 (the number of the deleted invoice) the new one is #65... and we really need to remake the invoice with number #64
So the question is 1) how do we truly delete an invoice with its number OR 2) how to make an invoice and force a number on it?