class Article extends DataObject {
   public static $has_many = array(
      'Reviews' => 'Review'
   );

   function getCMSFields() {
$f = parent::getCMSFields();
    $revManager = new HasManyDataObjectManager(
         $this,
         'Reviews',
         'Review'
      );
$f->addFieldToTab('Root.Reviews', $revManager);
return $f;
}

class Review extends DataObject{

   public static $has_one = array(
      'Article' => 'Article',
      'Owner' => 'Member'
   );
   
   public static $has_many = array(
      'Comments' => 'Comment'
   );
   function getCMSFields() {
    $f = new FieldSet();
   
$manager = new DataObjectManager(
$this, // Controller
'Comments', // Source name
'Comment', // Source class
      );
    $f->push($manager);
return $f;
}
}

class Comment extends DataObject {

   static $has_one = array(
      'Review'=>'Review',
);
   public function getCMSFields() {
      return new FieldSet(
         new TextareaField('Content', 'Content'),
         new CheckboxField('Status', 'Status'),
         new FileIFrameField('ReviewReport','Review file')
      );
}
}