https://theslyd.tumblr.com/post/161057960801/mini-tutorial-how-to-work-with-multiple-meshes-in

I was asked about this the other day. So I figure I write a mini tutorial on it.

When you clone an EA mesh, sometimes it’s divided into multiple meshes in the blender file, and often in an unreasonable way. Because Sims 4 Studio requires the blender file to have exact same amount of meshes when you import it back. This makes it very difficult to make changes on the model or transfer weight.

The solution is quite simple actually. Just join all the meshes into one.

1-2. In Object mode, hold Shift key and select the meshes one by one. Click Join. Do what you need to do to edit the joined mesh.

3-4. When you’re done editing, click the Scene tab and scroll down to S4Studio CAS Tools subsection. Make sure the Cut number is 0000. Save the mesh.

5. Open Sims 4 Studio and clone another mesh which has only one mesh as a base. Import the edited mesh, diffuse map, shadow map, normal map and specular map to this new base.

6. And don’t forget to change Sub Part Type under Categories tab. In this example, change it from Bra to Blouse. Otherwise your cc will show up in a wrong sub category and people might have a hard time finding it.

Below is a list of EA items which have only one mesh.

Female tops: clone the bra.

Female bottoms: clone the underwear.

Female full body: clone the chemise.