Hello, I've been writing around two or three different seperate stories, which have their own worlds that I'm building up. (Two almost from scratch.) A few years ago, I was working on a totally different but much more ambitious story. It comprised of multiple worlds, exploring through different time frames and a bunch of other stuff. At the time, it was the only story that I was working on. It was going to be my "Block Buster" novel series. xD But I set that story aside as I got older. I promised myself that I would work on it in the future, after my other 'smaller' book series. But now, since I've been building on three seperate stories, I was wondering... would these worlds that are seperate, that were intended to be their own works when they were finished, would they be appropriate to incorporate into my first story idea? In my first story, there were going to be 7 different worlds. 3 were modern, (and one had Earth in it,) 3 were fantasy based. I didn't do much world building at the time, since It was one of my first projects that I began with, and I was mostly interested in creating characters and magic systems. In the three seperate book series that I was going to make, they had their own magic, their own histories, and I'm in the middle of trying to map out their cultures and name different locations. (I'm doing one at a time.) Would it be appropriate to incorporate them into the first story's three fantasy worlds? I was excited about it when I had the idea, "yay, no work to do later!" But while playing around with it, i'm not so sure. All four were conceptualized as being their own, standalone book series, with little to no relation to each other. Plus, I still want to publish the first three series as their own series, either as spinoffs or something. I'll probably have to stay with the same publishing company if I do that, or if I publish these three online, I won't be able to publish my big, first idea with a publishing company in the future. (I'm assuming.) But the appeal of having three, pre-built, familiar worlds to look forward too when I pick up the first big story again, is very tempting, plus it could be fun trying to incorporate cameos and subtle references through out the different projects. Right now, I'm at odds, and I won't make any big decisions too soon. For now, they will remain seperate projects, but i'd be glad to hear any advice, suggestions or feedback.