If you'd like to sync your registrations of OPC or other registration forms with your k2 users and k2 groups, you may need to use this plugin which is a small modification of the original "user - k2" plugin. After installation please enable the plugin within joomla and disable the original "User - K2" plugin. The modified plugin is called "User - K2 Ext"
This is a modified plugin for K2 company based on:
* @version $Id: k2.php 1897 2013-02-08 17:13:00Z lefteris.kavadas $
* @package K2
* @author JoomlaWorks http://www.joomlaworks.net
* @copyright Copyright (c) 2006 - 2013 JoomlaWorks Ltd. All rights reserved.
* @license GNU/GPL license: http://www.gnu.org/copyleft/gpl.html