Edit terrain model

Hi

I have a terrain model created with open roads from simple Autocad points. Now have we discover a error in elevation of 5 point.

What is the easies way to fix this?

I have tryed with "Edit Terrain Model" from "Task > Terrain Model", but can´t because my terrain is "Not a editable Terrain"

I am using PoverCivil for Denmark SS4 vers. 08.11.09.789

Regards

Sigfús