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What I meant is something like this.

By using a mask/alpha map, I can set up multiple completely different shaders in one single material zone, controlled by where it's black and where it's white in the alpha map.

Here I'm using subsurface scatter on Antonia's skin, and a velvet material on her second-skin panties. You can see I used multiple Blender nodes: one to mix the diffuse materials, one to mix the different speculars, one to mix the bump.

 

Funny.. when I was trying to learn how to do this it completely escaped me.  Today running on about 3 hours sleep (had nasty battle with a UV map last night) just taking a quick peek at your shader....  it just clicks .. I totally get it.. so simple!