How Can I Separate a Mesh Into Two Separate Objects Without Corrupting UV Data?

Question

I'm working in Blender and Unity.

I downloaded my character from DeviantArt here, used Blender along with this addon to import the character's .mmd file to Blender, and saved her as a .blend file in my Unity project's folder. For some reason, when Unity imported her, her textures weren't appearing, so I created new materials and assigned them to the proper slots on the mesh renderer and she looks the way she should:

Now I'm trying to get my character's clothing physics working. I read online that Unity's Skinned Mesh Renderer and Cloth components are the best solutions, but it recommends that the cloth objects be child objects of the main body mesh. However, the character's clothing that I wish to add physics to (her skirt) is a part of the overall mesh.

So, in Blender I selected all of the vertices that make up the skirt and separated them from the main mesh, then saved a skirt.blend file containing just the skirt, then saved another blend file containing everything but her skirt:

After this process, the textures for the main mesh look just fine in Blender, and the UV data looks exactly the same except for the missing vertices that made up the skirt:

However, when Unity imports these files, it looks like the UV data is corrupted:

What's going on here? How can I fix the UV data for the main mesh?

Answer 1

I feel like a bit of a goof for not realizing that in removing vertices, I had changed the ordering of the UVs.

If I had to explain it to someone else with the same issue:

Imagine a drive-thru line (mesh) where 10 customers (vertices) place an order (UVs).

Now imagine that customers 6, 7, and 8 leave the line.

When customer (vertex) 9 comes along to the hand-out window (renderer), they're going to get customer (vertex) 6's order (UV) because no one removed the orders (UVs) that belonged to the now-departed customers (vertices).

All I had to do was go back into the inspector and reassign my materials manually with respect to the now-missing vertices and things are looking just fine.