Sloane Sisters

Style. Sabotage. Sisterhood.When Cate and Andie Sloane's Upper East Side dad met Stella and Lola Childs's British-model mom, nobody thought a transatlantic relationship would last. But then their parents drop the M-bomb — marriage — and it looks like Cate, Andie, Stella, and Lola are going to be one big happy family. Well, big anyway. Meet:Cate Sloane: She dominates the ninth grade at exclusive Ashton Prep. Tantrum-prone and competitive, Cate would rather wear Laura Ashley every day than be second best at anything. Luckily there's not a rival in sight. Yet.Andie Sloane: Twelve-year-old Andie…