Getting structure in single Threads

Hi all together,

I am looking for a solution to get some more structure / order in single threads. My current problem is, that I have single threads about a certain topic. where "subtopics" develop very dynamically. Because of the dynamics, a strict forum-subforum structure is not very helpful here.

Here an example:
Let's say, we have a forum about BBQ. Forum structure could be:
  • equipment
    • smokers
    • thermometers
    • accessories
  • recepies
  • general
In the forum "smokers" I have a thread about a certain smoker, where the users are discussing about buildup, quality, special accessories, most known errors, certain marchants and so on. Of course not in strict order, quite random through the whole thread.

I would now like to organize those discussion points in this specific thread. As these discussion points are very unique to the certain thread, I don't want a strict forum-subforum structure.

There is a possible solution, which is called Threadmarks:
Quite exactly the feature I need - but the marks are unique, which is not perfect for me. When I have 5 posts about a certain discussion point and I add a mark to each post, I have 5 identical marks in the threadmarks index list. When the number of posts is rising, there is no possibility to have any clear view in the index list.
For me, it would be better to have only one mark, which will lead to the 5 posts when clicking on it.

Another solution would be tagging. But tagging is not thread specific but forum-wide used, so the naming of the tag would be quite complex to make it unique for this special thread. Also I'd like to have a kind of dropdown list in each post, where the user can select the discussion point he is talking about. Or an auto-complete, when he types the discussion point, anything of this kind would help.

Do you have any other plugins which could help?

Thank you for your feedback!

One thing: My forum is a closed forum with 4 users, who are using xenforo to organize themselves. So the solution doesn't need to be mass-compatible. We could arrange ourselves to use a special "workflow" for posts, so the user-acceptance of any kind of solution is given :)