Really as @DTLow says, I can’t see an improvement on copy/paste. I do this a lot, I delete as I go often using cmnd + x, so I don’t get confused.
Make sure you keep a copy of the original doc of course in some other place, the problem is avoiding getting confused but I have found this the best way. I do it a lot. There are elaborate tricks on line but I have never found them useful. In effect one is editing and filtering as one does it, which is often what is really important.
