cookie path

Using the group id from punbb as a simple "login" ala:

    define('PUN_ROOT', '../../forums/');
    require PUN_ROOT.'include/common.php';
    
        //debuging
        echo $pun_user['g_id'];

        //check if in usegroup or die
    if ($pun_user['g_id'] == x || $pun_user['g_id'] == y || $pun_user['g_id'] == z ) {
    }
    else {
    die;}

pretty crude but it works

My base URL for the forum is forums.epixplx.com but when you load the page with this "login" part, you it uses cookie info from epixplx.com/forums and not it's base url.
So the users have too login too both, forums.epixplx.com (too read and post normaly) and epixplx.com/forums if they whant too load this page
Is it possible too make it use the "original" cookie from forums.epixplx.com?