As a parent to the child, can you allow the child to use your details to pass KYC verification, if asked? And if you do that, does it also mean that you are supporting underage gambling?
At the point where the child already won big but only needs to pass KYC to get the funds, I will actively help in getting the funds to him or to the family however, I will make a decision or mutual agreement with my child never to do it without parental guidance as it's against the law to allow under age gamble.
Yet the child will be grounded for a long time, not being able to do whatever he does, under serious supervision and this will let him or her to stay within check and act accordingly instead of putting us parents into trouble with the law.