How to add person to be primary on account for military discount

Hello, all.  I specifically asked if I could still get the discount for the military plan if I was the spouse of a military member and was told yes.  Apparently, that's not the case and I have to have my spouse (who is not on T-Mobile and uses a prepaid phone) be the primary.  I've emailed support and never heard back how I add him to the account and then make him the primary so I can upload his DD214 as proof of service.  Thank you to anyone who can help!