for Dead Girls Don't Write Letters by Gail Giles
Sunny Reynold's sister, Jazz, dies in a fire. Then one day a letter arrives, a letter from Jazz. A girl follows. But she can't possibly by Jazz--or can she? She seems to know all the family secrets, but Not-Jazz clearly has a few secrets of her own. Compelling, edgy, and suspenseful, Dead Girls Don't Write Letters will keep you guessing. And just when you think you know what's real and what's not, Gail Giles unfurls another surprise.
Publisher description retrieved from Google Books.