topsie... "There have been other disputes about whether a thread "belongs" to the person who started it, or to the other posters also. Does anyone know the answer?"

If it is obviously music or BS, it will be the "property" of the mod. If it is debatable, it is the property of the OP, subject to the mod's approval.

I have had threads moved against my wishes, but I bow to the mod unless I can make a case.

In any case, it NEVER belongs to other posters. It is between the OP and the mod.