I think that would make me feel powerless and start to cycle too, particularly if I were in a new environment, which is stressful to adjust to, to begin with, if someone's kid wouldn't obey and I felt there was nothing I could do to get them to stop violating my boundaries. It's tough with kids b/c if that were my little sister, I would have forcefully kicked her out, but when it's someone else's, how do you get them to do what you want, because the mom could get mad at you for your reaction?

Is that sort of what you feel in this situation?

Have you talked to the mom about this, and asked what to do?

Also recommend the book "Don't Shoot the Dog" by Karen Pryor. It basically discusses how to "train" animals (and humans). You ignore the bad behavior and reward the good, it tells you how. I'm still trying to get a hang of this "shaping" thing, it seems counter-intuitive to me.