Capturing Object Shadow in Post Process

Hello!

I’m loking in some sort Chromakey Post Process material, where I will be able to capture not only specific meshes via Custom Depth Buffer = True, but also their ground shadow projections. Something I like to achive - correct rendered object with it’s shadow on green screen.

So far I was achieve greenscreen and objects, and also was able to separate all shadows (not only ground projection, and not for specific meshes)