Require File Extension in NUMBER for CAD files during Rename

We generally have our Windchill File Name equal the Number including the file extension for CAD files. Sometimes the file extension gets left off by users when being renamed (it probably gets left off on both fields but the File Name will add the file extension automatically). This can cause some minor name conflicts if drawings and parts/assemblies have the same base names (TEST.drw and TEST.prt but both objects cannot be TEST without the file extension). Is there a way to automatically adding the file extension on the Number like the File Name does or prevent users from leaving off the file extension on the Number? We're on Windchill 10.1 currently.