Next in the series?

[Justice]

Let's discuss the next potential books for the series!
People theorize that this is simply a sidekick series, however it is not. This is a villain sibling origin series!
The first book being Anastasia and Drizella, and this one being Hook and his sister Marlene.

Here's my bets for DEFINITE future books in the series in no particular order:

1: a prequel about Han's and one of his brothers. (this seems the most obvious to me as there is so much to work with!).

2: a Stabbington brothers prequel about how they met Flynn Rider (yes please!)

3: Hades and Zeus

4: Ursala and Triton

Thoughts?