I was finally able to master exporting meshes from Marvelous Designer into the Sims 2 game, but there is a strange issue happening to the mesh. The entire mesh is showing up, but the sim's hands are invisible. I have never dealt with that before. I noticed when it first happened, I thought maybe it was because the sleeves are so long that I needed to assign bones to the hands, (which I needed to do since the sleeves are extra long) but even with that, the hands are still invisible. That is the only issue, though. I'm able to successfully export it from MD to Blender, create the UV maps, recolors, assign the right bones in Milkshape, it's only the invisible hands that is the issue. Since I have also never done meshes that involved long sleeves before, are long sleeves a different story than short sleeves in terms of meshing? Especially if they extend past the wrists? I hope someone can help, and I hope the solution is more simple than I think. Thanks! (Pics attached)

Long sleeves shouldn't be a problem once you've made sure there aren't any UVmapping or bone assignment issues with the hands.

The skin parts need to keep their original mapping, and no UVs of the shirt should be overlaying the parts of the skin that are still showing. If you only use one subset, you also need to avoid the pants-parts of the map, or you'll get issues with pants overlaying the shirt.

You can use the hands (and any other skin parts showing) from another TS2 mesh, so you don't have to assign the bones or worry about the UVmap for those parts. You can do this for any skin parts still showing.

Depending on how you're mapping the shirt, you can put it on a second subset, and keep the original subset for the skin parts. This is often done for 3t2/4t2 meshes and other items where the mapping needs to overlay parts of the skin and such, especially if you want to use a bigger part of the UVmap.

If you've already put the shirt (or hands) in a second subset, you need to make sure you've set up the mesh and recolor file are reading each other. The info in the PropertySet (subset names, etc.) needs to match up with subset names in the GMDC/GMND/SHPE in the mesh file, especially if you've added subsets or changed their names.
It's a good idea to keep the skin parts (hands) in the original "top" subset, and name the new subset for the shirt something else ("shirt" or "noblend" is fine).

That was it! I forgot to add a subset. The mesh I imported from Bodyshop didn’t have a subset and I forgot to regroup after I added the subset. It has been a minute since I last meshed. Thanks! It’s solved now!