We run a multi-site network instance of Wordpress at our institution. We synch our Active Directory daily in order to automatically create WP accounts for new users (e.g. basically subscribing them to our root site ourinstitution.sites.edu.
One user has created a subsite in which some of the content is public and some they wish to be only available to members of the institution.
Is there a plugin or easy fix that would automatically register a user (who already exists with an account in the network) as a subscriber of this subsite when they click on a link to this private area?
We don't want to subscriber everyone automatically. It'd be an opt-in.