Decals in Unreal: Can you have different alphas for different elements of the decal

Hello, I was experimenting with a realistic water puddle decal, and have run into a problem, the middle of a puddle should be flat in the normal map, shiny and dark, the sides shiny and dark, and the very sides dark.

Therefore, I’d need to have a different alpha for the diffuse, the normal and the smoothness. I’ve done so with 3 decals on top of each other, with different materials, but it does not seem like a clean way to work.

Experimenting with the latest version of unity, the decals there are 3 alpha slots to do exactly that. Does unreal possess something similar? Or a workaround?

Thank you