I should add, knowing the parents is a huge plus. Kids learn everything from their parents...knowing the parents are good people tells me a bit about the teenage daughters.  I also don't worry if the girls are relatively young (like 13-15ish) if they live nearby my home with their parents in the neighborhood. Obviously it's nice if they're old enough to drive for convenience sake. That's assuming they come to you...I don't mind bringing the kids to them depending on the situation.