Historically, it has been challenging to add section views to an existing Civil 3D section view group. Usually it required recreating the views, followed by some additional "intervention" to correct any manually created annotations or geometry. Fortunately, Civil 3D 2018 has made this task much easier with the introduction of Section View Drafting Buffers.
The new buffers act similar to AutoCAD’s Crossing Window Selection in that they recognize all manually created content that falls within the buffer or crosses over its boundary. The purpose of the drafting buffer is to ensure all content associated with a section view stays with that view if it is moved. Using this new feature, one (or more) section views can be added to an existing view group and any resulting “shift” in views will automatically include all of the manually created entities!
If you are interested, I’ve created a quick video that demonstrates how the new drafting buffers make it easy to add section views to an existing section view group…