Manny & Lo (1996)

Two sisters, 11-year-old Amanda and 16-year-old Laurel, run away from their different foster parents and sleep in model homes and wherever else they can. But when Laurel becomes pregnant. they realize they can't handle this crisis on their own. With nowhere else to turn, they decide to kidnap Elaine, a clerk in a baby-supply store. But Elaine seems to need Manny and Lo just as much as they need her.