Hi, I have an IMAC,and a MacBook with multiple family members as users plus iPhones and iPods. My son accidentally left his iPod home so he asked me to update it and send it to him. When I signed in under his user acct. I was asked for an Apple ID and password so I put mine in. Now all of his music doesn't appear in ITunes but my music does. Is there a way to find his music again? Thank you in advance.