Prequel to the Prequels have already been done in books Like the Darth Bane trilogy, the Kotor games, the star wars chronology, The Knights of the Old Republic Comics, Tales of the Jedi and Sith War comics.

In novels they uncovered the Machinations of Papatine to Unseat Chancellor Valorum through lies and treachery. That novel i believe i cannot recall the name was the prequel to episode 1.

The Prequel to episode 2 was written by Alan Dean Foster.

Labyrinth of Evil i believe was the Prequel to Episode III.

The prequel in book form to episode IV is Dark Lord the Rise of Darth Vader, and a further prequel to episode IV was delivered in the forms of the Force Unleashed Game, and Purge comics.

The far future Series which would be set more than a hundred years after the Legacy of the Force Novel series is the Legacy comics.

The skywalker Bloodline continues into this series.

Any farther back than Anakin Skywalkers birth would there be stories of an Earlier Skywalker bloodline was Shmi the first Skywalker to give birth to a force sentitive Like Anakin or did anakin have jedi ancesters or whatever the force users were called before the existance of jedi. I think they were called Whills, or WHill users and also called the ashla. The ancestors of the sith were called the Bogan.