at&t rebate form.. How do I get the promotion card?

I am currently under family plan and I recently bought a phone with my dad because I can't buy a phone alone because I am not authorized to do that. so I bought a phone(I paid for the phone) and got this rebate form and in that form there is the fill out box for "Subscribers name" and I was wondering if I should put my name or my dad's name for this box. does it really matter? or if I put my dad's name and they send my that promotion card, only he can use that card? please help.