I'm creating a simple directory from the user accounts and want to simplify it as much as possible for the users. I changed the label on nickname to Lastname, Firstname so that the users can be alphabetized by the nickname field, but I want the display_name to default, or even force, to the nickname field. I haven't seen a plugin, so I'm looking for something I can add to the functions to do this. Any ideas?
You can force this with a hook that activates when the profile is updated. The next step would be to hide the