With the completion of Book Three: Leonis, Volume One is also finished. I made a graphic to show you how I (currently) plan to separate the books into volumes:
Yes, Volume One is "only" three books. As that volume is subtitled Foundation, these three books had to set up all that follows. In Book One: Earth, we set up the Final Five and their flight to the Colonies. In Book Two: Gemenon, it's the conflict between monotheism and polytheism there that later becomes part of the Cylons' programming. In Book Three: Leonis, it's setting the stage for the conflict between Leo and Virgo, one that shapes everything that happens in the Colonies for a millennium.
Volume Two: Evolution is just that. How these different worlds evolve and how they are shaped by their masters who live on far away planets. I get cracking on that in short order, starting with Book Four: Virgon.
Thanks for reading.