[@Framing A Moose] 
A. Everyone has allie of some sort. No villian is completely on their own. 
B. If there wasnt even a chance of her father accepting it there is no reason to allow it. The idea is bind the villians to heros in a way that will make them hesitate to attack. Without that there is no reason for her to be in the program. 
C. They could still reproduce so children are still possible. Magic can over come alot.