Adding materials to complex landscape material

Hi there,

Was wondering if anyone could provide some insight on how i could add some extra materials to an existing premade landscape material that i’m having trouble understanding.
I’m using the landscape material from the “Boy and his Kite” project, which has a pretty complex structure in the material editor that keeps leaving me confused. I’d ideally like to use this specific landscape material because it’s generating great looking cliffs, but i’d like the surface of my non-mountainous areas to be something more simple and smooth like concrete or even just a plain matte colour, that isnt in the existing material layers:

For anyone who has it already, its the M_Landscape_01 from ‘A boy and his kite’, but to anyone who doesn’t here’s more detail on the structure of the landscape material in the editor:

So, i’m not entirely sure how the actual landscape layers are being created, but given this structure would it be possible to somehow insert an existing material i have (for instance, concrete) or even just to add a new layer that was something simple like a texture or base colour? I don’t even mind replacing some grass layers if necessary (as i don’t need them) but I’m not quite sure how to go about it and any help would be greatly appreciated.