I follow my mom's training in this one thing - "My House My Rules". Even my mom obeys my rules in my house or she is not welcome. I would kindly ask the in laws and their kid to get a motel room and they can come over when you are home to watch over the cats only. I'd also disipline the little girl if she does anything in front of you. I DO disipline anyone else's children in my home and all our friends know it. Weird enough - their kids LOVE me. One little girl in particular was very spoilt by mommy. She threw a ball at my big screen TV (and missed luckaly) in front of us all. I YELLED at her and her mommy said "oh honey - it's ok. I'm sure she didn't mean to yell at you" and I said "Yes I did!!!!". Do you know that little girl sat by me the whole time she was at my house and not by her mommy. Kids don't like to be spoilt and they won't be in MY home. Debbie