For my Muay Thai camp, minimum is 30 sessions/ 6 months. And after your 6 months you can just fly out & in with another 6 months without Muay Thai class.
But if you would like to do "in country" extend you have to retain 500,000 baht in your account + new 6 months Muay Thai enrollment
0 baht to her account (under her name) and she can apply DTV on soft power route like Cooking or Muay Thai, unemployed is fine. She needs her own DTV visa