Tough shit. People can resell things they own, like for example tickets, so assuming she and her daughter obtained tickets legally (directly or indirectly, I have no reason to doubt they did, though I don't know for sure), by that act she was already given explicit permission to enter the venue and remain there for the duration of event.

If they don't like it, they can sell named tickets, and BTW since Girl Scouts are known for being vicious hooligans, maybe they should have instituted football-like regime up to and including stadium bans for their mothers.