I think it'll be hard to have an
intergalactic war inside the Sosycrewi Galaxy.
Karakris: I'd also suggest that, too. I thought of using my fantasy universe in the Sosycrewi, too, but it isn't as fun when we don't have so much in common, like common units. It'll just confuse everyone if one user uses Earthly years, and the official unit is solar dates, and then we can't really interact, as we need time for our interactions to make sense?
I think you're completely welcome to join with another species, though, like I made the Zarva for the wiki. You could also adapt your history to the wiki and then let the future progress within the wiki, maybe splitting it in two (I can imagine that being slightly boring maybe), or with a main one whose elements are copied and only details, units etc. edited.
Personally, I don't think it's a good idea to have humans and our solar system within the wiki, because they exist in the Milkyway Galaxy, not the Sosycrewi Galaxy. Maybe one person could make humans/Sol.