It would probably be better if you made those into their own subthreads elsewhere on the post and just linked them beneath the boss battle comment for ease of finding them later, actually — that'll save the NPC Boss Mods from getting a bunch of notifs to their inboxes from a thread that doesn't need their immediate attention.

ICly it's fine if people spectate and whatnot, sure! But if you're planning on doing a bunch of threading amongst yourselves, it'd probably be better to do it elsewhere on the post and just link a jump between the boss battle comment that originated it and the new thread where the scene continued, if that makes sense!