You indicate he "moved" from NM to GA on his date of separation (assuming he was already in GA when he separated service. That is done at his name on the Personal Info page.
Then finish ALL of the Federal section...every scrap, not worrying about the states section yet.
Then you will work on each state's part-year tax returns...that is where he will tell each state shat part belongs to NM (all income up to his separation) and what part is GA's (everything after his separation...assuming he was already in GA when he separated).
Of course, your income.....if any, may figure into those forms too depending on whether you were claiming NM too before his separation...or not.....but you can assign your income on the part year tax returns too.
I normally tell people to spend a month working--printing--correcting--printing etc, before filing because they can be confusing...but.......................................