The Sisterwitches Duology is a subseries of the Antebellum Collection consisting of two books, The Sisterwitches: Part One and The Sisterwitches: Part Two. The series will explore the characters of Isadora and Sanna long before the events of the Network Series.
The Sisterwitches was originally envisioned as a singular novel, but when she realized that the story was much more expansive than she had originally intended, author Katie Cross decided to split the story into two parts.
Like the Network Series before it, The Sisterwitches was to be a young adult fantasy. But Cross realized, along with the broadening scope of the story, that it was turning to be more of an epic fantasy.
As of May of 2017, Cross was still working on the story and told readers on her Facebook page that she considering changing the title of the books to The Dragonmaster: Part One and The Dragonmasters: Part Two, as "it's as much about the downfall of the Dragonmasters as it is the Sisterwitches who survive it."