Careful.
it does work like that but you are supposed to be a family at the same location. If you look in the Family Sharing link that was sent in the location section, it says…
“Location requirements work the same if you're sharing your YouTube TV membership with a family group. The family manager sets the home area, and all family members must primarily live in the same household.”
Right now I think you can have 5-6 but only 3 actively watching it. Not sure if they are going to allow multiple people watching Sunday Ticket at the same time? Assuming you’d tune in using the current YouTube TV app.