<b>A teen actress has to wonder: In the cutthroat world of commercial modeling and acting, can a happy family be reality?</b><P>On camera, it's easy to be part of a perfect family: A director has hand-picked your parents after a week of callbacks, and the right things to say are printed on cue cards. Off camera, reality is a bit more complicated.<P>     Cassie Herold knows her parents are having problems. Her dad basically lives on the road and sees her more on TV than he does in real life. Her mom, a math professor who would rather balance an equation than get a manicure, is nothing like the energetic, perfectly groomed f.m.'s (fake moms) she sees at auditions for everything from snack cakes to energy water. If only Cassie could get her real life to be a bit more like her commercial life, then maybe she could get a date with Rory Roberts—the cutest boy in both the commercial <i >and</i> the real world. But will her family ever get back on track and be picture perfect?