Julia Roberts' young niece, Emma (previously seen in "Blow"), has just signed on for the movie adaptation of Sarah Mlynowski's "Bras and Broomsticks." Flick tells the tale of "an angst-ridden teenage girl who discovers that her socially inept younger sister -- and not she -- has inherited her divorced mother's magical powers. Despite the mother's warning not to cast spells, the younger sister succumbs to temptation, with disastrous results." Susan Cartsonis ("What Women Want") will act as producer for Fox 2000 Pictures.