First, I know that you can switch between the three city story lines early on by signing with a second city thereby abandoning the one you selected first, but have never done so and so don't know what needs to be done.

What I don't know is if this can be done once you've completed the entire expansion story. I finished WoTG having done the Windurst story, can I now re-start with one of the others?

If so, can someone please give me a pointer to what I have to do to reset the story.

Thanks.