Three Spare Keys to the X-blade

Brittany, Alison, and Molly are three ordinary girls who were raised on Earth by Sora and Kairi. They each discover that their origins are quite different from what they had been told. Brittany, daughter of Riku. Alison, daughter of Xehanort. Molly, daughter of... well Sora and Kairi. They get separated and secrets come out. This is one fic you won't want to miss out on.