I’ve struggled with this a lot. I’m assuming by out of line means they’re trying to do their own thing. I’ve done a lot of short skits starting from 8th grade and have built a pretty solid team on good people to work with that work with the team. I’ve encountered a couple people like this, and usually, if it’s not working, I won’t work with them the next video, but while they’re on set, and assuming you’re the director, you want to be neutral. Don’t take sides. You have to do the unfortunate and awkward talk by saying, “hey, I value your contributions and are glad that you’re trying to take charge” but you have to remind them that it’s a team effort. Hope this helped.