This seems like a pretty straight forward question and hoping not a poor question but here we go.
If you have a pigtail for three wires (say # 14 AWG if that makes a difference) together in a wire nut but you want to add another wire to the mix. Is the proper method to undo the wire nut and untwist them and try to straighten out all three as best as possible? (In IT there was a tool to straighten ethernet wire but haven’t seen such a thing for Romex). Then line up all four wires (new one included) so they're parallel and retwist again from scratch and wire nut it with a fresh new wire nut? Seems like a commonsense answer but with all things in life you can never be too sure and curious if professional electricians had a technique of their own to share.