You define new shares in Settings -> Computer Management -> File Share Distribution Points.  
The correct way to migrate to a new share would be 1) to setup the server with appropriate accounts. 2) Add the share in JSS location above 3) Open Casper Admin and select the new share  4) click Replicate (or clone or whatever it is).  
Then go into the JSS path at top and set the second repository as the primary/master.  Finally, you can remove your old repo.  
                
     
                                    
            Hiya,
Thanks for the reply.
To clarify, we aren't creating a new share but moving the Share location from one disk to another, on the same server.  So I did the process manually, removed the old share name, migrated the data manually then re-created the share (with the same name) and re-added all of the account permissions etc.  My understanding was that as long as the File Share Distribution points and HTTP info pointed to the right location it would be OK?
The File Share Distribution is fine, but the HTTP is not.  So if I undo those steps and replicate through Casper Admin do you think it will migrate the HTTP info to the new location?
Thanks,
Emma
                
     
                                    
            Okay! So the symlink in /Library/Server/Web/Data/Sites/Default needed to be updated with the new share path.