You can filter the user list in the chat and show only (custom) friends of current user in it with the help of our WordPress filter named iflychat_get_user_friends_filter.

Here is sample code to do this:

 

function my_custom_friends_filter($friends) {
  
  /** Get current user information **/

  global $current_user;
  get_currentuserinfo();

  /** Get friend list of the current user with the help of your custom function 
   * It will be an array containing friends id like array('2','5','7')
   */ 
  
  // $friends = get_friend_list($current_user->ID);

  return $friends;
}
add_filter('iflychat_get_user_friends_filter', 'my_custom_friends_filter');