Among the Hidden (The Shadow Children)

Government regulations limit families to two children each, so Luke, an illegal third-born, must live his life in secret, hidden in his family's farmhouse. When a new housing development is built on land bordering his backyard, Luke discovers Jen, another "shadow child", in one of the new homes. Jen is willing to risk everything for a chance to come out of the shadows, and her determination draws Luke into a dangerous gamble with high stakes.