Just one interesting question: are you planning to throw Dirty Pair to
this continuum of yours?
 If you are, it would be easy to explain how Crystal Imperium and
UG relate to each others: basicly when humanity had populated planets of
our solar system (Crystal Imperium in other words) and reached to other
places, Queen Serenity (or some other) brought out the idea of uniting
force of humans so they could give decent oppose to other, older and more
powerfull galactic forces (Yurai and others).
 In other words: CI is one of the founding and most poverfull (it *is*
whole solar system of nine planets) members of UG.
 You only need to get K&Y to meet Ranma on some place and stage is clear
for more...
 There ya go, if you found any of these ideas interesting, use it/them by
all means as you like.
KK