I'm fine with having them, I think it fits him. Gives him the chance to peep on girls from afar, makes him majestic in sack too *Chuckles* yeeeeaaah. But his sister will have the power of a Siren, since you want a villain to be in the band with Adam then she could be a singer/bass. Uses her singing to attract men, which gives them allot of their success. If that's ok with you, of course.

Edit: And if you need help planning stuff, I'm here. Coming up with plots/arcs are sort of my specialty/job in most RPs I help with.