In my Mod NE Enemies, I change the terrain when Enemies die.
In my Mod Bio Industries, I have it that you can use fertilizer to change the terrain back to Medium Grass.
For some reason tiles that were changed when biters die, now get's captured by blueprints.
As you can see from the screenshot, the base terrain is not captured, only the Medium Grass tiles around the areas that I changed when a biter died.
I'm not sure if it's a setting I'm missing. Force issue...
Both Mods are in my signature.