Child reset self as Family Organizer

I do not have an iPhone, but my 13yo child does. The phone was initially set up with my old iTunes ID. My kid reset the password and made herself the "adult". She removed parental controls. I considered doing a factory reset, but she would lose photos and voicemails from her dad (who passed ~3 years ago). While these things might be backed up to the iCloud, that would be in MY account (which she is using as the "adult") which I do not want her to use. I need to be the adult with the parental controls (obviously...she undid this somehow).

I changed the PW for my iTunes account and deleted Snapchat from her phone. The new PW needed to be entered in order to use the phone. I entered the new PW and voila, she was able to download Snapchat again.

How can I make myself the parent again and assign her a child's account with controls? Especially considering that I do not have an iPhone and we don't want to lose the precious photos and voicemails? In the meantime, the phone is in my possession.