Aren't the twins in collage? Wouldn't her rights be gone by now?

20 is adulthood in Japan. They had to turn 20 to become lovers with Keiichi. So, yep, her parental rights and obligations have expired. Now, it's all up to the boys, but knowing plot conflict in Yaoi, she'll want to take them to Mars or some shit. Maybe, exploit them as idols too. LMAO