The Potter Girl: Surprise- You Exist!

Harry has a little sister that only a few people know about. As far as the wizarding world is concerned, she doesn't exist. But now Harry's facing the prospect of leaving his little sister to fend for herself while he goes off to Hogwarts. How is the world going to react when they learn Harry isn't an only child after all? And how will Emma survive a year alone with the Dursleys?