Oh, OG. I am not entirely sure what nomuse meant there.Interobject reflection isn't really a feature in Carrara, I don't think, unless it's another name. The term refers to more of a phenomenon where one surface relects off another. I think they might be referring to a reflection map.(Might be neat to see what caustics look like...however that would kill render time.)

No need to think outside the box....
    Just make it invisible.