Potentially maybe she wasn't meant to join them, and was meant to go back to the Republic straight away. If she made the choice then, it could be written as that she decides to join them for the mission instead of returning to the Republic. Per chance, at least.
I don't understand what you are trying to say. Is English your first language or is there possibly a language barrier here?
Have you read the book or are you just trying to interpret the article I referenced?
I'm curious if someone has read the book and can definitively clear this up.