xprofile_filter_field_edit_name( string $field_name )

function xprofile_filter_field_edit_name ( $field_name ) {
    $is_field_edit_mode = false;

    $current_field = false;

    if ( bp_is_profile_component() && 'edit' == bp_current_action() ) {
        //we are on profile > edit screens, we should display alternate name, if available, instead of main name.
        $is_field_edit_mode = true;

        //we can use global $field variable here
        global $field;
        $current_field = $field;
    }

    if ( !$is_field_edit_mode && bp_is_register_page() ) {
        //We are on registration page/form. We should display alternate name, if available, instead of main name.
        $is_field_edit_mode = true;

        //we can use global $field variable here
        global $field;
        $current_field = $field;
    }

    //@todo : Should we do it if an admin is editing user profiles in backend ( wp-admin/edit-user.php... ) ?

    if ( $is_field_edit_mode ) {
        $alternate_name = bp_get_the_profile_field_alternate_name( $current_field );

        if ( !empty( $alternate_name ) ) {
            $field_name = $alternate_name;
        }
    }

    return $field_name;
}