Family Sharing - Forgot Passcode I Set for My Child

I set passcodes for each of my children so they would not be able to change their settings. I forgot the 4 digit passcode for one of my children and I can't seem to remember it. How do I figure out how to get that passcode so I can adjust her settings? It's not the same as forgetting my own passcode and having to do a hard reset of the iPad.