I wish they guys at the factory would improve the site surface tools. One way would be to give us a tool that would let us link points so that the line linking the points defines a change in level and points either side of the line cannot interact with each other but can grade from the line to the point on either side. This would be great for defining road edges and top of banks. The tool should work so that you can link points of differing elevation in a way that the joining line provides a constant change in level along its length between points.
A bit of a confusing description I could probably illustrate it better with a few diagrams but who has the time.