I’m not sure if I understand this.
Your end goal is to have a render of a sofa with a shadow of a person sitting on it, without seeing the actual person, right?
Correct - it’s much easier to render shadows and get correct colours/falloffs/angles than it is to fake them in PS, see examples attached. Files should be named appropriately
In this instance I can get away with leaving the 3D person visible to reflections and just patch the sofa back in, but i’m pretty sure that’s not how it should work