Storyboard, part 1 · 8:25pm Jan 20th, 2013
Soran and Kia are brothers, and are (unspecified how many generations) descendants of Sora and Kairi, hence there names.
Dea means goddess in Italian, Santo means saint in Italian, Musica means music in Italian, Sole means sun in Italian (but Sol seemed like a better name, and also Sol means sun in other languages), and Senza means Without (empty, hollow, heartless) in Italian. Mare means sea or ocean in Italian, and is the name of the clan Chrysalis mentioned in Chapter 6.