Sorry for being Late, I am busy this week hence not Posting much on Forums.
Do you mean Cloth/Material will modify the Light that Pass Through it? Unfortunately that is not Possible without Path Tracing (as per my Knowledge). Unfortunately I have not worked with Path Tracing so I cannot Guide with that in Detail.
But as Game Developers we often use Secondary Light (Spot Light for that) for that Purpose with Higher Softness and Light Radius to Control its Diffusion and on other Side we use PBR to alter Material to React Accordingly which it mostly does by Default with little modifications.
You can choose either of above Solutions depending on your Work.