Shadows Over London by Christian Klaver

Justice Kasric's world is turned upside down when her father forcibly bundles the entire family into carriages in the middle of the night and carts them off to a strange mansion on the outskirts of London. The Faerie are invading-and the Kasric siblings don't even have a chance to stay neutral, because different members of their family are working for opposite sides. 

But Justice isn't your average fifteen-year-old girl growing up in Victorian London. She's an irrepressible scoundrel, and she always has a plan. These qualities have ostracized her from the rest of the family before now, but even her older siblings look to her to help them escape. Justice certainly isn't going to stay locked up once she discovers the world of Faerie, especially once she and her siblings discover magical talents they never knew they had.