A Crack in the Line by Michael Lawrence

Alaric's life has unraveled in the two years since he lost his mother in a terrible train crash. He and his father are barely speaking, and their home, Withern Rise, is in shambles.

Naia tries not to dwell on the accident that nearly killed her mother two years ago, now that life with her parents at Withern Rise has returned to normal.

Alaric and Naia do not know each other, or that they are living nearly identical lives. But when they meet, their resemblance to each other is unmistakable. As their lives entwine, they uncover a truth that has the power to rearrange, or even erase, their very existence. (FIC LAWRENCE)