Music Sharing - Different iTunes Accounts
You can share your music with your relative by either burning it on a CD for him, or copying the music from iTunes to an external drive.  All he has to do when he gets home is copy it to his computer and set it up so that Apple TV can stream from it.  I would not recommend syncing the music to his iPad, he will not be able to remove it from his iPad. 

Music that ripped from your CD's should copy over just fine.  However, some iTunes music is linked to your Apple ID, so when he copies it to his computer, his computer must be authorized to use your apple id content.  You can authorize your iTunes account on his computer by going to store authorize this computer to use an Apple ID.