Thanks Kevin! Your suggestion worked. It actually prompted me when publishing that it was copying the scripts folder and did move it and update the original script correctly.
One other thing I found, in my original script, I had a few imports to modules from the 3rd party site-package I mentioned. Those modules weren't used in the script, they just hadn't been removed from the import. When I take out the 3rd party imports and publish, then ADSSurface.py is copied to the server. When I add back the 3rd party imports and publish, ADSSurface.py is NOT copied.
In either case, if I follow your suggestion using sys.path.append, then ADSSurface.py is copied over and everything works.