Currently it is only possible to define an include/exclude by a specific objects, with the exception of CMasking_Mask element.
This makes it incredibly difficult to include objects that are in XRef Scenes as they are not directly selectable.
The include/exclude options across all of Corona (lights, cameras, render mask, maps, caustics etc.) should be expanded to allow an include/exclude based on layer, GBuffer ID and unified so that the same selections can be made across any tool where an include/exclude might be necessary.
Submitted on AHA Ideas (CMAX-I-19).