H.S.
I have to identify with the lady at the supermarket. I would never in my right mind go on vacation with my in-laws. We have a very strained relationship, my MIL continually babies my husband, and even refers to him as "brother" in front of his own children, because that's what they called him growing up. Either way - it's not a healthy environment, and I wouldn't subject my children to it. I certainly wouldn't ruin a family vacation by inviting them along, especially to Disney World, no less. Not every family benefits from extended family interaction. Sometimes it can be downright unpleasant, and bad for everyone involved.