Quote Originally Posted by Kittra View Post
If the bust slider is any indication, you wouldn't need to redo anything, because the game already compensates for it.
All the bust slider shows is that the game engine is capable of expanding the mesh while adjusting the texture in a way it doesn't look stretched from outright resizing. Basically what Lowtech became famous for within the same model and through an in-game slider instead of applying a separate mesh.

Increasing butt size means that physics applied to skirts, loose straps and flaps would have to be recalculated (assuming XIV's game engine is anything like 3-D max or having something as primitive as MMD's bullet point engine), and depending on size would probably need more polygons to not look blocky when animated. You could make a case for skirt rigging already being questionable (Vanya sort of shows this), and adding a more notable round object in there would clip if you only increased butt size and adjusted nothing else. It's never a matter of just expanding the mesh and making the associated objects bigger; there's a little more involved (again, based on my experience as I don't know the intricacies of FFXIV's engine).