Summary: Keep elevations of certain vertices of feature lines 'locked' when doing an auto-balance of volumes in the Grading Volume Tools

Description: When doing an auto-balance of Volumes in the Grading Volume Tools, the whole base feature line of the grading moves up or down to balance volumes.
Sometimes, some vertices of the base feature line of the grading need to keep their actual elevation (e.g. when some vertices are draped on a Surface).
It would be nice to be able to 'lock' certain vertices of the base feature line so these are not changed in elevation when auto-balancing the grading volumes.

Product and Feature: AutoCAD Civil 3D - Grading

Submitted By: Pieter Haeck on 11/17/2015