How many beers is appropriate to be drunk before…

How many beers is allowed before going to an amusement park with your boyfriend as a girlfriend.. however! You’re meeting the girlfriend’s side of the family. The boyfriend is sober if anything high on weed. And family that y’all are meeting with is the girlfriends younger sisters (all adults) and their boyfriend and younger sister who is 13. The rest of the group isn’t drinking but the oldest girlfriend is drinking however everyone is driving separately. For me it depends on the behavior of said person who is drunk. What do y’all think?