Wasn't there ways to get through the dimensions into other ones? If that's the case than I say go for the split ones but give random characters a chance at random intervals to enter a different dimension. Like say you want to split up a group. Then you have an opportunity to split them up. From how much of the game i've seen (Haven't completely finished yet) it's happened at one point or another. At least I think that's what happened not completely sure on the matter 'confuses self'.