When merging a thread with more than just a few messages into an older one, ask yourself this question: Would you rename the old thread’s title to that of the newer thread? If not, don’t merge them. If you’re not sure, then either change the title of the older thread to the newer one, or don’t merge them. (And of course, if “yes”, then merge + rename.)
Ah, this thread has been bumped. In that case, in light of the recent threads around being kind – I apologize to the OP for a previous comment on this thread that could have been interpreted as rude. I swear I meant it in jest, but I shouldn’t have said anything at all.