Remember to Copy and Paste to Original co-ordinates when you open a drawing that says it's a
"FOREIGN DWG File.
This DWG file was saved by an application that was not developed or licensed by Autodesk. What do you want to do?"
This will always remind you to copy it into your Civil3d DWT to make sure all edits will work correctly.
The Paste to Original Co-ordinates button on the ribbon can be found on the Home Tab under the Panel name of Clipboard to the far right hand side. If you cant find that one i always use the Edit pull down menu and it's in there as well.