For one, the party numbers for centers would be popped down, assuming the new faction got it's own territory, hence adding scenes. Also, added IDs in the codes might cause an hour or two of delay, going through the code and changing everything referencing the new faction, and on top of that there'd probably be another page of banners, so right there that's added scene props, map icons, tableau materials, and meshes.
It's not too big a deal though, it'd only take a few hours to sort it out, and if you're organized and know what to look for it might take less than an hour.