public static $summary_fields = array(
      'Rating' => 'Rating',
      'Member.Email' => 'Email'
   );

      $oFieldSet->addFieldToTab(
         'Root.Ratings',
         new HasManyDataObjectManager(
            $this,
            'Ratings',
            'Rating'
         )
      );

      $oFieldSet->addFieldToTab(
         'Root.Ratings',
         new HasManyComplexTableField(
            $this,
            'Ratings',
            'Rating'
         )
      );

[User Warning] Can't figure out the data class of
GET /testss/admin/security/EditForm/field/Members/item/2/edit

Line 28 in G:\localhost\testss\dataobject_manager\code\HasManyDataObjectManager.php

DataObject::add_extension('Member', 'Expert');

<?php
class Expert extends Extension {
   static $singular_name = 'Expert';
   static $plural_name = 'Experts';

   function extraStatics() {
      return array(
         'db' => array(
            'Description' => 'HTMLText',
            'TitleName' => 'Text',
         ),
         'many_many' => array(
            'Pages' => 'Page',
         ),
         'has_one' => array(
          'Thumbnail' => 'Image'
         ),
      );
   }

   public function getCMSFields() {
      $fields = parent::getCMSFields();
   $this->extend('updateCMSFields', $fields);
   return $fields;
   }

   public function updateCMSFields(&$fields) {
$fields->addFieldToTab("Root.Main", new TextField('TitleName', 'Academic title'), "FirstName");
      $fields->addFieldToTab("Root.Description", new SimpleHTMLEditorField("Description", "Description"));

      //This does work and shows the many many relation is working
      $fields->addFieldToTab("Root.Pages",new CheckboxSetField('Pages','Pages (check all that apply)', DataObject::get("Page")->toDropdownMap()));

      $domPages = new ManyManyDataObjectManager($this, "Pages", "Page", array('Title' => 'Title'), "getCMSFields_forPopup", '', 'Surname ASC');
      $fields->addFieldToTab("Root.Pages", $domPages);

$fields->addFieldToTab("Root.Thumbnail", new ImageField('Thumbnail', 'Thumbnail'));
return $fields;
}

   function getCMSFields_forPopup() {
      $fields = new FieldSet(
         new TextField("Surname", "Surname")
      );
      return $fields;
   }
}

<?php
class Page extends SiteTree {
   static $belongs_many_many = array(
      'Members' => 'Member',
   );

   function getCMSFields() {
      $fields = parent::getCMSFields();

      // It works fine from here
      $manager = new ManyManyDataObjectManager($this, "Members", "Member", array('Surname' => 'Surname'), "getCMSFields_forPopup", "", "Surname ASC");
      $manager->setPermissions(array());
$fields->addFieldToTab("Root.Content.Experts", $manager);

      return $fields;
   }

   function getCMSFields_forPopup() {
      $fields = new FieldSet(
         new TextField("Title", "Title")
      );
      return $fields;
   }
}

class Page_Controller extends ContentController {

   /**
    * An array of actions that can be accessed via a request. Each array element should be an action name, and the
    * permissions or conditions required to allow the user to access it.
    *
    * <code>
    * array (
    * 'action', // anyone can access this action
    * 'action' => true, // same as above
    * 'action' => 'ADMIN', // you must have ADMIN permissions to access this action
    * 'action' => '->checkAction' // you can only access this action if $this->checkAction() returns true
    * );
    * </code>
    *
    * @var array
    */
   public static $allowed_actions = array (
   );

   public function init() {
      parent::init();

      // Note: you should use SS template require tags inside your templates
      // instead of putting Requirements calls here. However these are
      // included so that our older themes still work
      Requirements::themedCSS('layout');
      Requirements::themedCSS('typography');
      Requirements::themedCSS('form');
   }
}