Alright, I have a confusing problem. The Russian Wrap top here http://www.medievalsims.com/forums/...hp?f=241&t=8962 and the teen version here https://darkmoon689.tumblr.com/post...e-textures-from.

The fat morph doesn't work with some bottoms. For example these bottoms here. https://fracturedmoonlight.tumblr.c...pants-so-we-all When paired with the top and set to fat morph the top doesn't fatten up, but the bottoms do. But on other bottoms the fat morph works fine. I thought that it was the bottoms problem, but then I found another set of bottoms where the same thing happened, the skirt here. http://www.medievalsims.com/forums/...hp?f=225&t=5646

It happens with the teen versions of the same outfits as well.

I'm sure I've heard of how to fix this somewhere, but I cannot remember how. Can anyone help?

The issue can happen if the top isn't properly set as a top morph. If that is the case, fixing the mesh comments should be enough.

I remember this was an issue with some untuckable tops (on HPs mesh and a few others, but it was fixed later). That is where I heard of this issue, anyway. Had some problems with this mesh way back when I decided to make maternity top recolors, and randomly got the bottom-half belly even if the top had a pregmorph. I assume the same problem also can happen with fatmorphs.

EDIT:

These tops say
MorphNames: botmorphs fatbot

Proper morph comments for tops are
MorphNames: topmorphs fattop
and
MorphNames: topmorphs pregtop

while proper ones for bottoms and fullbody outfits are
MorphNames: botmorphs fatbot
and
MorphNames: botmorphs pregbot


To fix them:
Extract the GMDC (right-click/extract) for the top you want to fix
Import to Milkshape
Fix comments to match the above ones
export as GMDC/SimPE file
Reimport into mesh file(right-click/import).
Save.
(Delete cache files before running the game or Bodyshop - old references after mesh edits are sticky)

https://hermit-fox.livejournal.com/1740.html (reference/tutorial)

Ah I see! That's rather embarrassing, because I opened one in Milkshape to see if anything was wrong and totally failed to spot that.

Thanks!