Question Reuse layers in real world heightmap generated from gps logs.

I have real word off-roading place and I can npw generate automatically heightmap from gps logs. I can add programmatically trees, rocks and so on. Problem is when I have more logging, then I have new more accurate height map. if I replace height map, I lose layers. In screenshot routes are painted using small trees to mark where draw road layer.

So routes, trees and other things are always in same place. Only heightmap is better when more routes are recorded.

If I draw layers looking right way, is there way to reuse those layers with next better height map?

Is it possible programmatically draw layers?

 

Simple resolution just replace heightmap using c#.