I don't see why so many people are advising Ree-Xi to limit her time with her family over a ten year old kid. She obviously enjoys the time with them as evidenced by her post. It sounds like they had a great time overall.
Ree-Xi has already leveled with her sister on the issue and I believe sister told her basically that it is what it is with the kids.
For what its worth, when my nephews and nieces come over, they eat what we put out on the bar, or it sets until they want something else at which time they see the same dish. But, my wife "don't take no crap."