how to make small detail craters in lunar landscape

trying to find a way to paint small impact craters in the same way that foliage paint works. I have a mesh and a crater normal map and a mask for the mesh. So far I can only get this to work with the material blend mode set to Masked which gives a hard and visible edge to the crater. What I would like to do is blend in the edge.

I’m new to Unreal and suspect that I’m going about this the wrong way.
Any advive would be welcome.