User blog comment:Doom Vroom/Sequels and Sequel Advice/@comment-10789912-20151013151236

The difference between a series and a sequel is major. In a direct series, the story has been planned for such, and each story continues the plot, sometimes feeling like one adventure. A sequel, however, is more tricky.

A sequel should continue the plot, and teach the readers more than we found out in the first story. It should elaborate on the details, without overdoing it. A sequel, at heart, shouldn't be a "part II". It should be a continuation.

Disconnected sequels continue the story, lore, plot, et cetera, without reusing the same cast of characters (or introducing plenty of new ones), can use the same, or a different, setting, and generally feels like a new story in whole, with a related, or the same, antagonist.

Either route highlighted above could do you well, but be careful in which one you pick. See, I've noticed some authors have extreme troubles writing one, but not the other. It is always good to push and test yourself to evolve as a writer, but know your specialty.

More important than anything else- you, as the author, should feel it is a worthwhile investment. When you look at the finished product, you should both feel, and see it as a true continuation of your original work.

It seems your story will either be a disconnected sequel (new characters), or a timeline/"what if?" situation, where events happen differently. Just make sure it feels right to you before adding it to the wiki.