BuddyPress.org

If you put it in functions.php you’ll probably need to do something like this:
function auto_login_bp() {
//Automatically log the user in
$user_info = get_userdata($user_id);
wp_set_auth_cookie($user_id);
do_action(‘wp_signon’, $user_info->user_login);
}

add_filter( ‘wpmu_signup_user_notification’, ‘auto_login_bp’ );

Although, even then it might not know the $user_id variable. So, you might have to add the code in my original post to the bp-auto-activate-user-and-blog plugin on line 170 or so. Although, that will cause the issues I mentioned above I think.