DD has had sleepovers with her grandparents and my sisters from about 6 months old, then with her cousins from about 1. They all run in a pack and she loves it.
The boy cousins all generally end up together and the few girls often sleep at our house.
DH's stance is to make sure that toile ting or drying after bath time, he is with our DD and me doing any visiting kids. If the girls jump in our bed in the morning, or even in the middle of the night he's never next to a visiting child in the bed, there's always our DD or me between he and another kid. He would put all the sleeping girls in with me and sleep on the matress. He feels uncomfortable and doesn't want to be in the position that little girls are to snuggling up to him. Kind of paranoid, but I guess you have to be as a man who has great relationships with all of his nieces and nephews.