Thank you for replying!
I described my workflow, because since I discovered automatically grouped sessions on TMUX, I'd never want to use a terminal multiplexer without that, or comparable functionality.
What I do:
* Open new terminal with a hot-key
* This terminal automatically joins my local (default) session group
* All windows in this session group are now available
* Most windows connect to remote TMUXs
* With CTRL+ 4 keypresses I can navigate to any preexisting window/session, or create a new one locally (or on a remote host)
* After using the window, either i close the terminal, and/or the window, depending on if i want to keep this one.
* On the remote end, people can join my sessions, and can independently of me navigate in the remote window space.
* if I need to concurrently see two (probably different) windows of my local/remote window grid, I just open/auto-attach another terminal.
* the above makes it easy to "place another live tmux view" on a screen different than my main screen, for presentation, or teaching purposes.
Everybody (who previously used tmux in non-grouped mode) I've shown/explained this setup to, has setup their environment just like it afterwards.
Thanks for the other info too :)