gistfile1.php

<?php

// show.php
class Show extends AppModel {
  var $hasAndBelongsToMany = array('User');
}

// user.php
class User extends AppModel {
  var $hasAndBelongsToMany = array('Show');
}

// Trying to add association between existing User and Show records:
// $show_id = existing show's id
// $user_id = existing user's id

$data = array('Show' => array('id' => $show_id), 'User' => array('id' => $user_id));

?>