Snow Layer Material

Hey there I have a little problem with the layered snow material I just want the snow on the top and that work but my problem is how can I deactivate the normal map of the base material there wehere the snow is ? Here are some pictures of my problem and some of my shading network.

Use the same layering network (which you are using to generate the top down / Z-axis world position mask) and just filter it with a rgb/3vector blue (0.5,0,5,1) which will create basically a normal map that is flat, or of course replace it with another that simulates snow better.

A flat normal is (0,0,1).