Self-Illumination with Shadows on the object itself - How to achieve?

[BeneZ]

Hello,
I need self-illumination to get exact background from movie replicated, which means there must be a black diffuse to have no double lighting.
But I need shadows of new 3D scene objects on this background.

I know only a complicated postproduction workflow with a shadow-catcher, but I would like to have a material, that allows already to see those shadows in the vray render.

How can I achieve this? Ist there a way with composite or blend material?

Thanks for help

[suzanne_doherty]

What about the VrayOverrideMtl ?

[fixeighted]

I'm not sure I understand exactly what you need for this, but why wouldn't having the background plate as a background in the VFB work with a shadow catcher?

Regardless, I did just discover that with this example I have the self-illuminated image camera mapped onto the geometry, then
using just the shadow catching plane it doesn't work properly, however if you do put anything (in this case the same image) in as a
background layer then the shadow catcher then 'sees through' the camera mapped part, for whatever reson...odd though.
Maybe some part of this might work for your setup, or I'm missing the point