I followed this tutorial for importing and setting up custom shirts/pants
https://youtu.be/a3aqWQ26KV0?si=AR3sZluLfVEZGSJ5

When I initially imported the shirt/pants, it looked like this.
(Even though i used the exported CC fbx character in the app where I created shirt / pants, but that's another story).
In the app that the shirt / pants were done, they fit fine....but in CC4 they did not fit, they looked like below.
(I did not set up and apply any materials yet, that would be done in Unreal 5.3)
W

Following the YT tutorial, I was able to fix 95% of the issues....
It still need some fixing, but I wanted to see how it got imported into Unreal 5.3.



The important thing to do is when exporting the fbx file...
To export it using the current pose.
Otherwise import into UE5.3 will have pose and clothing out of sync.

Interesting....I tried this...
I re-imported the fbx I just exported and it looks the same as it does when I import it into UE5.3.
It does not look like the one that I exported.

Another BIG issue is that when I import custom pants, if it is not conforming to figure, I will run collision on it...
It almost always tears the mesh....usually it will tear a zipper opening.

That's because the cloth mesh you imported is not solid to begin with.
It's already ripped, but you do not see it because vertices at the rip line occupy the same space.
First thing you do after the import, is go to Mesh > Edit Normals and run Auto smooth with Merge Identical Points checked.



This might not work if the distance between vertices at the rip line is beyond certain value.
In whch case you have to fix it at the source app, or export with appropriate settings to solidify the mesh on export (like from Marvelous designer).

Thx....that fixed the rip.