If you are on thier gamercard before it's switched to invite only they can join but that's only once.
Ugh I know a *** I flipped on badly cause of this. I was in a party kicked him he got back in. Then i was like u dicks r inviting him so I kicked everyone and he still joined a Invite only party with me alone in it Sevel Its been bothering me badly. Two Werd if you dont want a Kid joining in ( Host Boot ) I got so pist I flooded him offline for a day.