Example: Replacing Section Entities
You can redefine a section (sketch) and replace entities, even after the sketch is used to create features. The children of the replaced entity are automatically rerouted to the new entity.
In the following example, an entity is replaced in the sketch that was extruded to create a cube.
1. Open the sketch.
1. Line to be replaced
2. Sketch a new line to replace the first line.
1. Line to be replaced
2. New line to replace line #1
3. Right-click line #1 and choose Replace from the shortcut menu.
4. Select the new line, line #2, to replace line #1. The new line replaces the old line.
5. Trim the portions of the vertical lines that extend beyond the new line.
6. Click 
OK.
OK.