iPhone parental controls- school contact loophole

Hi,

I have pretty strict parental controls on my child’s phone including not allowing them to add new contacts or communicate with anyone who is not already in their contacts.

Unfortunately, my kid to have found a way around this by adding someone’s number as “school” (instead of “home” or “mobile”.

The person texts or calls them and then they add the contact from there.

I can’t figure out a way to turn this off. It feels like a pretty glaring loophole.

Would love to know if anyone has thoughts or tips.

Thanks