Make sure you're using a VPN. I also use a MAC address spoofer for great justice. Be safe, be careful.
I would leave a tip regarding the descriptions of the individuals and children involved (your girlfriend could also go through the missing children database), and the fact that they appeared to be interviewing for au pairs which means they put out an advertisement. They could preliminarily investigate to ensure that the ads were from legit people. I'm guessing that the requests aren't going to be so overwhelmingly burdensome that they wouldn't be able to figure out if she's overreacting or not. It can also be anonymous, but honestly, I would leave a name and number because they might want to follow up and do a sketch if they find any more suspicion around the claims.
Okay, just go to Encyclopedia Dramatica and search "Doxxing".