Take your “Layer Sample” node and hook it up to your alpha pin. I was always clear what to connect there. You said you tried it but it did not work. You did not say that previously. What didn’t work?
Simple setup. Two layers as functions with UV input. “LAYER SAMPLE” is only alpha. The name of the layer needs to match the name of a layer in the landscape tool, just as your “Layer Blend” nodes would have to match.
On the terrain I painted a U. Notice the different layers are at different scales:
Now here I will add heightlerp using a checker pattern. The “checker” could be a texture or anything, doesn’t matter:
The affect on terrain is to modulate the paintable layer with the supplied height input:
Here is multiplying by checker instead of heightlerp. Thats like an additional mask:
Here is the result on the landscape: