Allowing your child to use your ID to pass KYC is not just supporting underage gambling—it's empowering it actively coming from legal and ethical principles.
It could be treated as fraud by most firms because you misrepresented the actual account holder, to some countrys legal consequences are attached to such act for both parent and child, the account can equally be banned or winnings seized when discovered.

Personally it is tempting to refuse such huge win considering it is a life changing one, but we should have to ask ourselves some tough questions before engaging into it

* How did they get access to it?
* Am I not encouraging this behavior if I help now?
* What could happen next time they try again?

Sometimes "helping" means refusing and setting boundaries, especially when it feels hard to do it

This is just my opinion on this comment thought.