Becoming my sister / V.C. Andrews.

Like everyone else in Palm Springs, Gish idolises her smart, beautiful, kind older sister. Even their parents compare Gish unfavourably to Gloria -- threatening to send her to boarding school once the more perfect sister leaves for college. But Gloria has an unwavering love for Gish, even if that connection belies a weariness with her own accomplishments. Wanting a better life for her overlooked sibling, Gloria teaches Gish how to talk to boys, embrace her femininity, and finally develop a life of her own. And just as life is looking up for Gish, Gloria meets a handsome, mysterious boy. Obsessed with the stranger, Gloria closes off her life to her sister -- then disappears without a trace. A police search yields nothing. Their father's manic investigation proves fruitless. And their already starstruck mother becomes increasingly lost in daydreams of the celebrities who partied in their house decades ago when the town was a Hollywood getaway. Untethered from the weight of her sister's presence -- but also missing her sister's love -- what will Gish do with this new terrible freedom, with this sense she could become anything?