Sorry all, I've been procrastinating on this for too long. I may be able to get him to AT&T store this coming week and talk to a rep. about getting him put on my plan for $10.
Went to the store today. they were able to put his motorola razer phone on my plan and keep his number. Only 20.00 per month unlimited talk and text / no contract. They also adjusted my plan because of the additional line so now my total bill (with the additional line) is only $2 more than what I was paying.