Is it possible in Cycles to have faces with alpha, overlaying diffuse faces in a single material? I am working with UDIM in Blender Cycles and I am trying to work out a particular problem, but that is really not important.

I have broken my problem down to its most basic parts, and here is what I would like to accomplish:

I would like to use only 1 material (node tree) for an entire object and have part of the object, lets call it the face, as diffuse and yet have another transparent part of the object, lets call it the eyelashes, overlaying the diffuse...all in the same material. Can this be done?
Create two node groups ( or two simple  shaders )  in one material ( each act as a separate material )
you will use one output and a mix shader, the mixing factor comes from a comparison against a known limit of the UVmap created for this purpose only, as in the following setup :