How to clean up after multiple questions were posted as one question, then reposted individually

Question

A user asked a question with multiple unrelated parts (three problems and their answers from a book, which the OP wanted help in understanding). Someone advised that the different problems in this "question" really should be posted as three separate questions on the site, so the OP dutifully started to post the questions individually.

The OP also expressed willingness to delete the original question. But in the meantime, someone had posted an answer to the original (multi-part) question, addressing the first problem in the list. The OP accepted this answer.

It's unclear to me what advice to give to the OP on how to clean up this situation (if indeed it needs "cleaning up"). I suppose that deleting the question at this point would (at least in effect) delete an answer that evidently had some value and had earned the answerer some reputation.

Provided that the reposting of the first part of the question doesn't itself get any upvoted answers, I suppose that in this case the original (multi-part) question could be edited by removing the second and third parts (which weren't yet answered). This isn't a general approach to all such situations, however. (For example, answers to two different parts might have been posted.)

Or is this just the sort of thing to bring to a moderator's attention?

Answer 1

In this particular case, where there was no duplicated effort, the best course of action would be to edit the original multi-part question to include only the part which was answered, and possibly links to the other parts (and to leave a comment explaining what you did, since it is a major change). This prevents the problem from worsening if people read the question, not realizing that parts of it are a duplicate. One could put a close vote as "duplicate" on the duplicate with no upvoted answers - or, in any case, at least leave a comment to redirect would-be answerers to the earlier duplicate.

If they had received two answers to the same question in different places, I would recommend making a similar edit, flagging for moderator attention (to suggest that they merge the questions, since they would, in this case, be exact duplicates), and casting a close vote as "duplicate" on the original multi-part question (since this is likely to take effect faster than moderator action and is also less likely to get declined).

If the original question got an answer including multiple parts (or, actually, this could apply in any of the cases), it'd probably be best to vote to close the original question as "too broad" or off-topic (with a custom reason) and to leave a comment on the answer asking the answerer to separate their post into answers to the corresponding new questions - and to delete the original answer to allow faster deletion of the original question and avoid having duplicate answers (and it would be courteous to upvote their new answers in this case)