Say, there is "maxim" vs "aphorism" question. I want to know the difference between "tenet" and "maxim". Do I edit the first question, extending it with the new concern, or create a new one?
I think you have answered yourself: a new concern is a new question. One important consideration is that adding a new concern would invalidate, in part, every answer which has already been posted.
You should edit
- to fix grammatical or spelling mistakes
- to clarify the meaning of a post without changing it
- to correct minor mistakes or add addendums / updates as the post ages
- to add related resources or hyperlinks
[from edit questions and answers]
but should not edit to change the meaning of the post.