If she is school age or turning school age the school with probably approach them. If their doctor hasn't. Mail, no return address, them with a type list of free and low-cost activities for the summer. Is her birthday coming up? However if they are not interested or unwilling there is not much anyone can do. This does not seem to be severe enough to warrant medical neglect. You don't seem to have a lot of connection to this family so there's really little you can do. I would really stay away from dx'ing anyone. If she's infatuated with you may I suggest setting up a reward system. Where every (time period) she doesn't do (most annoying thing) you'll put a sticker on your door when she gets ( number) stickers she can come down and do an activity. I've always had lots of interaction with neighborhood kids so I tend to treat them like my own. I'll have more suggestions based on age soon.