Thank you for the GPs.

This sounds like a fun challenge! Does the structure need an overall outline? For example, in I, Robot, rather than an ongoing saga with a complex web of interrelated stories, you just have separate stories tied together by the rules of robotics, how they apply, and how they get you in trouble. There is an element of culture that crosses all the stories as well, since the stories all take place in the same fictional world, and some hints that the various interpretations of the rules of robotics result in gradual changes in the society that created the robots and those rules.

Maybe you could just define some key... thing, or concept, or societal structure, something that inspires you, and then brainstorm all the different stories that could be going on seemingly unrelated, but in actuality, wholly related.

You could start by just brainstorming the society and key connection, and as you begin brainstorming the stories that would happen within the scope of those elements, you might find that some sort of outline structure appears - some chronology of the story that shows historical changes in the society, or maybe recurring characters, recurring objects, whatever.

I can tell you that if this were my project, I'd start by worrying about how to structure it, and at the end, I'd be wondering how to get the whole thing squeezed into anything less that 500k words, because I'm the queen of scope creep!

Any particular genre you have in mind?

Cheers,
Michelle