If I was doing this, I'd have my PI run into the parents somewhere they'd be waiting for awhile--like a doctor's waiting room, or a pharmacy getting a prescription filled, or waiting for a car repair. Since some of those things may be hard to predict, one sure-fire would be to have the PI start attending the parents' church under a fake identity, or join the parents' hobby or social club, or become a regular in the same restaurant or bar, or contrive to be next to them in a busy grocery line.
Maybe fake up a cell phone call to the fictional annoying kid where the "parent" (PI) is scolding the kid and hangs up and uses the apparently just-happened phone call as a natural trigger to start venting to the person standing right next to her----your targetted parent.
Your biggest expense would be the time the PI would have to take getting close to the target.
People who are afraid they did the wrong thing and desperately want to believe they did the right thing, as well as who have a financial interest, tend to get evangelical in their fervor and like to share their strong opinion about how what they did was right and other people should do it too. If your PI is even a halfway decent actor, the parents should bite. From the defensive desire to justify themselves and get some strokes and empathy even if their particular teen facility *doesn't* offer kickbacks they'll probably bite.
I am not blind to the irony about people being fervent and evangelical about their hot button issues. :smile:
Still, I think one of the reasonable checks and balances on parental authority in society is that blood kin that are close enough to potentially sue for custody, like a grandparent, have a right to know if the kid is sent to a facility, and which facility, because they have a reasonable, genuine, pro-social interest in the child's health and well-being.
Sometimes a child will really need residential treatment and the relatives will be wrong to disapprove.
Sometimes a child's parents will place the child in a poor-quality facility or one that is extremely inappropriate to the child's needs and the child's other blood relatives are the only *reasonable* people with standing to bring the problem to the attention of the family courts and child welfare system.
I don't know which this is, but if you have asked the parents once (or aren't on speaking terms with them), and this is your grandchild you're talking about, it's reasonable for you to use a PI as described to get the name of the facility so you can check on it and see if it's a necessary and appropriate placement, or if you need to hire an attorney and get the family courts or child welfare officials involved.
Once your PI has found the name of the facility, contact ISAC (google them) to get more information on whether you maybe should pursue this with the courts, or maybe seek some mediation with the parents, or leave it alone, or whatever action or lack of action is most appropriate to your situation and is in the best interests of the child.
Timoclea