I recently asked a rather broad question, with four parts. I quickly received an excellent answer which solved three of them, but the fourth seems to be less related than I thought, and is still unanswered.
I would like to edit the question so it does not include the fourth part, accept the answer I've been given, and ask the fourth part on its own as a separate question.
I know that substantially changing a question after it's received answers is frowned on - but in this case, since I'm not altering it to make an answer less relevant, I wondered if it would be appropriate.
(To be fair, it would make another answer less relevant - however, that other answer - while very helpful and interesting - doesn't actually answer the fourth part, so it seems a minor casualty.)