If you need to add Vertices to your Feature lines or 3D Poly lines this is how:

You have 3 places you can choose from to run command, command line, Pulldown Menu or Ribbon.

Command=AeccInsertFeatureElevPoint

From Pulldown Menu pick "Grading" > "Edit Feature Line Elevation" > "Insert Elevation Point"

Specify a location, distance, or increments at which to insert multiple points. When a single point is inserted, you can specify the elevation.

From Ribbon Menu pick "Modify Tab" > "Edit Elevations Panel" > "Insert Elevation Point"

When you just select the feature line the Contextual Tab will show up. You will then have to select the "Edit Elevation"  to get all the elevation options.