How can I add multiple answers installation in a single wordpress?

Question

With the instruction availble on Q2A I successfully added one answer settings to a wordpress account. I have to integrate one more answer site to integrate with the same wordpress account. Is it possible? I thought if we make a change in table prefix will add a new database in existing WP database.

Here, the following code in WP be the same as the new one is also a subdomain.

define('COOKIEPATH', '/');
define('COOKIE_DOMAIN', '.mysite.com');

The problem may arise here, as we want to add the following lines
at the end of the WordPress wp-config.php Once we forwaded to the
qa.mysite.com, consider the new installation in ta.mysite.com. 
How can I manage the redirection without any conflict.I don't have
a good knowledge in PHP, Please help.

/** To allow redirection from WordPress login to Question2Answer **/
add_filter('allowed_redirect_hosts', 'qa_wordpress_redirect_hosts');
function qa_wordpress_redirect_hosts($content) {
	$content[] = 'qa.mysite.com';
	return $content;
}