Material override... for X-Ref Scenes

This is such a small thing but would make a number of jobs easier. Would it be possible to included x-ref scenes into the exclude/include section of the Material override?

The reason being is that sometimes we do white chalk massing models on textured landscapes.

Cheers!

I’d like this too, but am curious if its possible for vray to even do this.

Xref materials can be overridden through script so imagine it is doable.