You can tick multiple roles against a volunteer account (‘volunteer’,’family coach’,’church coordinator’) and these will coexist happily.
Trying to combine volunteer and admin roles is not practiced. It's preferable to keep these separate so that people make a conscious choice to log in to either their volunteer account or their admin account. Of course if they’re volunteering in an area they’re an admin for then there’s nothing to stop them updating the system under their admin account. The only change that might be worth making to ease the coexistence would be to change the way the menus display. So at the moment, if you have admin and volunteer roles you’d see both menus. The preference would be for them to see just the highest applicable menu based on all the roles they have. I think this would make it a lot smoother.
Our process in the UK is that a family coach must be an approved volunteer but this can be as a family friend, they don’t need to have been approved to host.