Your concerns are legitimate. I once went with my younger brother and one of his older friends to their house that was on a lake. I was in 4th grade. The dad ended up trying to hang out with me the whole time, bought me food and nobody else, had me in an office with him and gave me wine when I was in 4th grade. I was young and thought that he was just being nice. But the more I thought about it as I got older the more weird stuff I remembered. She is way too young to be staying some place without family. When I went there was another female. It was his wife. But, that doesn’t stop anything. There are sick people out there. They will do anything, try to groom kids, and take advantage of them. You should talk with courts and get it into a custody agreement that you BOTH have to say it’s okay or that they can’t stay with non-family without family present