Allow more than one accepted answer, if answers refer to different (sub-) questions
38540
Wouldn't it make sense to have more than one answer acceptable?
128234
Asking for more information on a question or answer
115812
Allow locking of answers
76545
changing your answer to match someone else's
16806
Accept Multiple Answers or Split Bounty among Several Users
12116
Two Answers, One Question
103155
Does Stack Exchange allow for answers which question the validity or stance of the original question?
148502
Two accepted answers
104491
Single question thread with multiple questions, some duplicates
90717
How do I combine two answers to create the best answer on stackoverflow?
148715
Should the system cap the number of answers allowed for a specific question?
32895
How can I avoid asking duplicate questions?
124174
Make accepted check more distinct from non-accepted check on own questions
242
Accepting your own answer with alternative answers to be worth +2 reputation?
56823
Change how questions marked as duplicates by the asker are represented
116860
Is it poor form to switch accepted answers?
111135
Asking upvote for accepted answer