security - WP Developing

Is it possible to add user roles beyond those defined by default by Directories Pro?

This currently can only be achieved through custom code. The below would allow for adding custom roles:

add_filter('drts_wordpress_roles', function($roles) {
    $roles[] = 'my_user_role';
    $roles[] = 'my_other_user_role';
    return $roles;
});

In a future release, addition of a settings interface for enabling/disabling custom roles is planned. (I assume this also means that one will be able to add/remove custom roles using this same settings interface).