*Reallusion Tech responded about Vertex assignment and soft cloth that there is currently a technical problem working together with cloth vs cloth but..

I believe it's your cloth tracking with vertex assignment having a conflict with Clothing assigned with soft cloth and using cloth in general and enabling cloth vs Cloth increases the potential for failure exponentially.

To help prevent incompatibilities between Vertex and soft cloth with cloth vs cloth enabled, I believe users would need to use this workflow:

*enabling soft cloth on skin, make the vertex assignment option disabled.

*For beards and hair etc they could be converted to clothing, you can then have Cloth tracking applied to the full body without conflict. You could in the future hide the fact that the hair and beard is being converted to soft cloth and give it a different label such as "Fully body Tracking Enabled" - which becomes enabled if the users enable the skin as soft cloth. - in the future you might relabel this to "Skin Physics" so it's a little more intuitive to users.

***This could work now if you expose the setting to users: Toggle option of cloth tracking when users enable skin as soft cloth.*** Currently you only have cloth tracking applied to only the head region. I've made animated morphs work with skin physics - there is so much potential here beyond the limitations of vertex assignment.

For performance, you could disable the tracking of cloth if there is none covering a particular area and or if there is no morphs.

Cloth tracking may also be used to pin bordering skin materials so that physics weightmaps can have grey stokes across materials to influence physics anywhere because currently they have to be painted black on each border material.

If you prefer, you could send me an R & D version of either CC4 or iC8 to test cloth tracking set to track the entire body with cloth physics enabled on skin then I can test cloth vs cloth/clothing to inspect clipping/penetration of either cloth.

This could be an easy solution and rival Unity's $7 million Ziva skin physics system.

Joint driven morphs can further enhance the realism https://www.youtube.com/watch?v=tBNyGtLi1dE&ab_channel=Reallusion

Or Joint Driven Displacement mapping of muscle groups using a variation of your SSS human shader material specifically to target displacement and the normal map strength. This would offer users the ability to customize skin physics easily and accurately.

This SSS human shader variant may also be used to change color of areas of the skin material. I guess you guys did follow through my suggestion when you created the wrinkle system! great job on that! so expanding the Wrinkle system to the entire body with displacement, color and normal map strength driven by joints would be amazing.

***All physical shape influences the skin physics, not just how the weight maps are painted***

*Fast physics baking mode, a minimal mode Quick shader should be added to temporarily hide the viewport/and or switch to smooth render for all scene items.