How do I add layers to materials imported from SketchUp

This is a basic question that I still don't have an answer for, so I thought I'd finally ask! I can't seem to find an answer in the material guide or in past forum questions...

When I export a model to KT and open it up to work on the materials, all of my SU materials are there but they are all one layer. I can't figure out how to add another layer to these materials. If I open the material in the Material Editor and right click on it the menu only lets me "Set Layered Material" which basically resets it to a black material, so I lose whatever color or bitmap was on the material.

I've been using a workaround by using the "Set Layered Material" option and then putting the color or bit map back in, but it seems like there should be a way to add a layer to these materials without resetting them....I just can't figure it out!

I don't believe there's a way to keep the previous settings since a layered material starts empty.
Though, in the advanced settings you could copy/paste the old material into a new layered material as a layer... a bit tricky I think, do it worth?

Thanks for the response...I think doing it that way is just as complicated and time consuming as the way I do it now...!

Here's an example of what I want to do:
I make a complex model in Sketchup and use a bunch of image textures. I export it to Kerkythea and open it up and now I want to add specular properties to these textures - which you are supposed to do with layers. But if I set the material to layered it erases the diffuse texture or color that it had and I have to go back and put it back in. This gets pretty tiresome after awhile!

That's what I was afraid of...but at least now I know for sure...thanks!