Rica, I just now saw your post about not getting opportunities because you get too many skill points while the heir is a teen. With my guitar-playing heir, I didn't let him get any skill points until he became a young adult. He didn't touch a guitar until his birthday (using the "Think" method from The Music Man). As I said, he only got one skill opportunity for guitar. And when he switched over to fishing because he obviously wasn't going to super-max the guitar, he still didn't get any skill opportunities for that. However, it's not file size that's causing the problem -- my 4th gen heir (his daughter) has received 3 skill ops.
Bottom line -- If your heir has a few skill points, he or she will probably get black ops (or not). But it's not a good idea to max the skill as a teen.