Sorry for necroposting, but i had the same need to show only related objects. I have many EventPages and many Members. Each of members can be assigned to each EventPage, but there are about 1,000 users and usually about 200-300 are assigned. So I did the next:

EventPage.php:

class EventPage extends Page
{
.
.
static $many_many = array(
      'Members' => 'Member'
   );

public function getCMSFields() {
    $fields = parent::getCMSFields();
      
      $sqlQuery = new SQLQuery();
      $sqlQuery->select = array('MemberID');
      $sqlQuery->from = array("EventPage_Members");
      $sqlQuery->where = array("EventPageID=".$this->ID);
      $rawSQL = $sqlQuery->sql();
      $result = $sqlQuery->execute();
      $query="MemberID=";
      foreach($result as $row){
         $query .= $row[MemberID]." OR MemberID=";
      }
      $query .= $row[MemberID];
      
      
      $modulesTablefield = new ManyManyComplexTableField(
$this,
'Members',
'Member',
array(
       'Name' => 'Name',
    'Email' => 'Email'
),
'getCMSFields_forPopup',
       $query,
       '',
       ''
);

$modulesTablefield->setReadOnly('true');

$fields->addFieldToTab( 'Root.Content.Subscribers', $modulesTablefield );

      return $fields;
   }
.
.
}

In Member.php from sapphire i also made some changes like
static $belongs_many_many = array(
'Events' => 'EventPage'
);

What is my code doing? It takes all MemberID which are related to the current EventPage from many_many table which in my case named EventPage_Members and had columns MemberID, EventPageID. Then I made a $query with that MemberIDs which is used as filter in ManyManyComplexTableField constructor.

This solves only one half of problem - i couln't remove that markers... Hope others could =)