The dress I'm trying to make is broken on the cas screen.

Hi. Extreme distortions like this are caused by the choice of the garment to clone. See that the distortion happens in the skirt area? This is your clue. Your garment is affected by skirt bones while the item you cloned to start the package was not. The solution is to clone an item that is affected by skirt bones ( like DressPanels ) and import your blend there

There are a number of other issues unrelated to the distortions:

- uvs generated in the default square uv space will stretch vertically when ts4 rectangular textures are set as the background. Before you start rearranging uv islands, make sure to shrink all of them back to the original size  with S Y 0.5. Right now the skirt uv island is stretched;
- speaking of uvs, do not scale them individually unless the difference in the texture quality is acceptable. Right now the skirt is much smaller than the upper half of the dress, there will be noticeable difference, especially if you will apply patterns;
- you should delete more of the body covered by clothing. This way you will have more space to put your garment's uvs;
- try to avoid the bottom right corner because everyone puts everything there and you end up with cas full of items that cannot be used together;
- transfer uvs and weights with nearest face interpolated;


- dresses are vertex painted with two colors. You can do it manually or just transfer the vertex paint;

- split sharp edges before baking textures. See the black shadow at the very bottom of the dress?
- remove doubles on the body