AT&T Next out of contract discount questions

Okay. Let's say person:
1) me
2) husband
3) dad
4) grandma
5) best friend
On my account. I have att next on people 1-4, but 4 wants to keep her phone and not upgrade. 5 hasn't upgraded in years and would like an upgrade on next. Do I have to enter into a contract again on 4 to keep the discount or will I still get the discount since I'm not upgrading her?