How to sync multi site users so that they can access the WPMUDev 'Support' plugin?

Hi there,
I'm just starting out with multisite, but I have a question.
I'm using subdomains for my multisite network and I wanted ALL users of the newly created sites to be able to access a central support service.
I've installed WPMUDev 'Support System' and network activated it, but it does not do what I was hoping that it would.
I would like it so that my main site is the only site with support enabled and I would like it so that users of the subdomains can access this support system only. In other words, they should not have a support area in their subdomain, but can automatically get access to the main site support system install.
I know that the users are not created in the main site user list, but instead added to their own domain list, but I was hoping that there was a way to get around this?
Perhaps users can be added to the main site at the time that the subdomain is created?
I don't knew, but I'm hoping that you can think of a clever way to do this for me!