Force Usernames

Does anyone know how I can force a user to use the displayName field as a user’s Nickname in another user’s roster?

I can’t auto populate the rosters because the user list is too long, so I want users to be able to add other users to their roster. But the username field is a user code, not their name. I know users can put that in themselves, but the default Nickname is the sAMAccountName field, and I want it to be the displayName field and lock it that way. If I take the Rename button out, I must make sure the Nickname is correctedly added.

I’m using Openfire 3.8.2 on a CentOS server, with AD integration and a PostgreSQL database. I’m adding users on Spark 2.6.3.

Thank you.