add new controller function to rails_admin

We are using rails_admin plug in to manage back end for a classroom. There is an admin(Coordinator) and several moderators(Teaching assistants). The admin and moderators should be able to add students to the database. Each student is associated with a moderator(TA). When a moderator clicks to view the students the rails_admin renders all the students in the database. How can we restrict rails_admin to show only those students whose TA is the moderator who is logged in? Admin should be able to see all the students in the database.