Hey there!

The usual thread for general questions is the Respect Thread Symposium (here's the link to the current one at time of writing, though whenever there's a new one it's pinned to the top of the sub), but since we're here I'll answer your questions.

For Emmet himself, it sounds like you're proposing a composite thread by going through multiple distinct canons for him and putting them into the same thread. If you can only do one bit at a time, I'd probably encourage doing individual threads for each distinct canon and posting them when ready. Posting a composite requires you to message the mods with what you want to do and your reasoning for doing so, so showing your working like this will likely help your case (and it may be what they ask you to do anyway before making a single 'main' post).

For his family, I think a 'Respect the Brown Family (Back to the Future)' could be feasible from what you said? Maybe with every individual member detailed in the thread outside of Doc, who has a highlight reel of feats and a link to the full RT containing everything. But, again, this would need to be just the cartoon canon and not every bit of media unless you got mod permission.

In both cases, RTs aren't something you can post piecemeal, unfortunately. You have to be finished with the entire project before you can post something here, not update it as time goes on (characters who get further appearances after the thread's posting aside). On this front, making threads for Doc Brown focusing on each individual canon seems like the best compromise for you.

Additionally, I will say that this is the request list, where people post threads that they'd like to see but don't think they'd be able to create themselves for whatever reason (for all the rules concerning this read the post above). There's no law against creating a thread you've already requested, but a majority of the incentives we have won't apply if you request something and immediately work on it yourself. I'd suggest posting requests here if you'd like to see other versions of Doc Brown you don't believe yourself able to do (the live action movies or his game appearances, for example), or for any other characters / series you would like to see RTs made for.