Edit Decal Blend mode Stain through code

Hey guys I am wondering if it is possible to change the way decal blend mode stain works . It seems as though it is multiplying color and metallic. but not roughness
Is it possible to change the blending mode code of the stain mode under the hood somewhere . for example changing it from a multiple to a hardlight blend mode like in photoshop.
If so can someone point me in the right direction of where this may be located.

Thanks heaps