Transferring iTunes data onto new phone from different account
I have shared my iTunes account/Apple ID with my kids and now they're getting older. I'm getting ready to get one his own phone and number, and it makes sense to get him a new Apple account. The question is, how can I transfer his music and his games out of my account and into his? It doesn't make sense for him to have to rebuy and restart everything and I don't want him to use my Apple ID now that he's getting older.
iPhone 6s