Can’t access iCloud email because account is locked - but need email to unlock account.

So... it’s a circle jerk? Idk. My kid was signed up for an iCloud account a long time ago, but when his phone broke (at 9 maybe?) and we gave him a “new” one, his dad signed up for a new iCloud. Oops. No biggie, right? 3 years later, his old iCloud is still on our family sharing (with a 6.99 mo sub) and we can’t remove because he’s under 12? Tried inviting that forgot account to a new family, but ...his old account is “locked” and the only option to unlock is to sign into his email and get the code. But. Lol. Can’t sign into the iCloud email because his iCloud account is locked! Wtf? We don’t have the phone it was initially set up on so now I’m just confused. I get it, no biggie, but I want my other kids’ Apple ids on family sharing and we’re one one short! Also, Idk, 6.99/mo for 3 years is like, 250? I coulda bought like 1/4 an iPhone with that. 🙄