OSTicket add user to multiple departments

The job is to allow users (staff) to be added to multiple departments. At present on the Admin panel/staff/selected user, a user can only be added to one department via a dropdown (see figure 1). We would like to add users to multiple departments, we need to be able to see all the departments listed with tick boxes next to each department so we can select which department we would like to add the user to(see figure2).