BuddyPress.org

I found how to restrict name changes here: https://buddypress.org/community/groups/how-to-and-troubleshooting/forum/topic/disable-name-change-in-profile/ , but am still having difficulty learning how to populate the the name with the entered username.
In populating it correctly I think I would use something like if (bp_the_profile_group() == “1”), but now i need to assign username to name.