Hi again. Sorry for the wait.
So there's a lot to unpack here.
1). Basically what i think happened here is someone copied slot rays interactions from one item ( yfBody_EP06LouisXVICourt ) to another ( yfBody_DressSunButtons ). This was really galaxy brained of them. I am not sure how exactly did they do it but am pretty certain that they did not input all of that by hand. I tried searching for keywords in the code but did not find any. Maybe it is easier to do in a different software? No idea
2). Pretty certain the author of this dress cloned someone else's package to make theirs. The name of the original file is removed, that one is custom. The mistakes they made in Blender are the type a beginner would make, a beginner would not think of editing slot rays like this;
3). Speaking of mistakes, this is a good example of why you should never use other ppl's cc as a reference on how to do things:
Some items are split into meshgroups to tune each of them differently. Glasses are split into two to assign a different shader for lenses. Hair is made of three where two are hat chops that appear when you put on a hat. The dress you cloned is made of 4 meshgroups to hide tall boots.
Anyway, s4s is just a packaging software that allows you to duplicate, preview and edit game content. It does not create items from scratch like the software Maxis uses. It is important to keep that in mind when you are importing something because what you replace was tuned to be affected by specific bones, to be positioned specific way, to interact with other items in a specific way.
For example, the meshgroup at the very bottom can be affected by foot, calf and toe bones. It has no slot rays interactions. It is tuned to hide or disappear upon interaction with the items in the same area in Region map. When you replace it with a full body, it introduces a lot of new bones, the slot ray information is not added, and region map is not changed automatically. You will be lucky if the game shows you what you've done wrong with distortions but it does not do that for everyone. If you won't get it, someone else using your cc might.
All area of the body covered by clothing should be removed.
Transfer a uv_1 with Nearest face interpolated
Skirt-like bottoms should be vertex painted with 3fff00 and the transition between them smoothed
The uvs created in the default square uv space will stretch vertically when a rectangular texture is set as the background. TS4 textures are rectangular so you need to bring them back to their initial size with S Y 0.5
It is best to not put uvs of parts that are meant to have transparency between arms because some skin creators fill that area with paint.
This was not the best choice of the garment for the beginner because adding transparency is tricky.
Instead of replacing the existing meshgroup with yours to enable transparency, you should split your mesh the same way as whatever you cloned, then duplicate the ( usually )last geometry of each lod in the warehouse( the most of the body), add it in Region map and LODs, then import the blend, and change the shader for the transparent part.
I do not advice to do what they've done and clone someone else's cc without permission, especially considering they already introduced new bones. I asked the developers
how to edit slot rays interactions fast so stay tuned.
This is what your blend file should look like. Keep in mind that the textures were compressed, so they would need to be remade
