@All (modders specially)
Okay I told you guys that I will be explaining Juri's C1 material setup so here you go.
So Juri has two eye patches and both of them are rigged such that one eye patch is rigged to regular face bones (head, cheek etc) and the other one is rigged to some special EyePatch bones. I don't know what's the purpose of having two exactly same eye patches but deleting one is not wise since both of them are properly rigged. I tried deleting the one that has normal face rigging but the other eye patch ended up clipping with the face whenever she speak so I kept both of them intact and that solved the clipping issues.
So how should we setup her materials ? check these images below.
When you import her in Blender (assuming you're using my character pack). You should see a default material setup like this.
The two materials in bottom inside the red box are both eye patches but for some reason the top one takes the name CM_F59_01_E05_SuitMain while the bottom one is CM_F59_01_Invisible.001, now I assume that Juri's C1 use some kind of dynamic shader changing or some similar technique that makes her eye patches disappear as soon as you use VT or CA, her covered eyelash also use a similar technique because originally her eyelash is invisible but as soon as her eyepatch disappears her eyelash appears.
So what I did I selected both eye patches and assigned them to CM_F59_01_Invisible.001 then deleted the empty group CM_F59_01_E05_SuitMain, that leaves us with CM_F59_01_Invisible (covered eyelash) and CM_F59_01_Invisible.001 (eye patches). Don't worry about the 001 because we are going to use the same material CM_F59_01_Invisible in UE4 for both of them so 001 is only for naming and differentiating the eyelash and eye patches.
Finally rename the suit material CM_F59_01_E05_SuitMain.001 to CM_F59_01_E05_SuitMain because that's the actual suit.
Your final setup should look like this
We have both eye patches in CM_F59_01_Invisible.001 (this will use CM_F59_01_Invisible in UE4), covered eyelash in CM_F59_01_Invisible (this will also use CM_F59_01_Invisible in UE4) and CM_F59_01_E05_SuitMain (this will use CM_F59_01_E05_SuitMain in UE4 as it is).
You can try assigning both eye patches to covered eye lash material CM_F59_01_Invisible so all of them will be inside this material and delete CM_F59_01_Invisible.001 but I kept it because it made selecting the eye patches easier.
Although this makes her eye patch work as intended but some things remain unexplained here, for example why there are two eye patches and both of them are rigged properly. What kind of shader switching Juri's C1 use to make them appear/disappear etc.
I hope this help you guys getting started with Juri's C1 mesh modding.