Since you give no particulars, I'd say read the VSS for dummies book. Everything controlling which materials are copied onto which figure is in the control prop Apply Rules and Shader Rules.

Quote - Also, if I want to use stuff like wet skin shaders, should I load them before or after synchronizing?

Whoa - back up. The question is nonsense, given what VSS is.

VSS is two things - a script which can be used for anything at all, and a set of shader templates for human parts. 

VSS, the script, replaces the shaders on your figure with whatever shaders you have in its templates. It does not magically improve other people's shaders. It throws them away and shoves the shader you load into the control prop onto the figure, while keeping the target figure's texture maps. This is a convenience and does not do anything magical - it could be done by hand.

The shader templates I published include 4 generations of different realism skin shaders, shaders for eye parts, and a couple non-realism shaders including a Vargas-style shader and a Toon shader. I also did a hair shader but I wasn't really serious about it.

So - when you use VSS, it is a short-cut, a convenience, for applying shaders and shader settings to the many material zones of a figure or prop, or multiple (perhaps dozens) of props and figures, from a single template shader. Thus, when you want to change a parameter, you can enjoy the convenience of doing it only once instead of 11 times. But you still have to decide which shader to use, or design your own, and either way you make parameter changes as you see fit. VSS won't help you design a shader AT ALL.

I have provided some shaders, and many people think they are better than any others, so you might want to use my shaders with VSS, but you do not have to. However, if you want to use some other shaders, you will have to load them into the VSS control prop, and adjust them to become reusable templates, so that they will pick up whatever texture maps are already on the target figure.

If you have wet skin shaders on the target (or any shader of any kind) they are going to be destroyed by synchronizing - removed completely - and replaced with what you have loaded in the VSS control prop.

To answer your question, if you load the wet skin shader and then synchronize, it will be deleted and replaced with the shader loaded in VSS.

If you synchronize, and then load the wet skin shader, you'll have the wet skin shader and the synchronization will be undone.

---

Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)