Subdomain redirect dashboard

I am trying to work out one last issue I am having with my WPMS setup. The primary website is: domain.tld. The users can register for a subdomain's. When the user logs into the dashboard it redirects them to their subdomain/wp-admin/.

I do not want this, I would rather them stay at domain.tld/wp-admin/.

This is important for me because user generated content needs to be collected on one server and uploaded to a object store. The other servers in the farm are simply slaves and do not store any user generated content. I have been messing around with the following code (as well as various plugins).

`// Redirect to https login if forced to use SSL
if ( force_ssl_admin() && !is_ssl() ) {
if ( 0 === strpos($_SERVER['REQUEST_URI'], 'http') ) {
wp_redirect(preg_replace('|^http://|', 'https://', $_SERVER['REQUEST_URI']));
exit();
} else {
wp_redirect('https://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI']);
exit();
}
}

Anyone have a suggestion to keep all users regardless of the subdomain logged into a single dashboard URL?