Sorry about the confusion, So If I'm logged into the master site then, I can register a new user account on one the slaves site without the slave site inheriting information from the master and sharing the session data? Essentially, I would be subscribing/creating a new shared user on the slave site...

If you are logged into a master site, could you complete a subscription form on a slave site as a new user without sharing the session data across the two sites? Basically, the slave site would just see the logged in user of the master site as a new site visitor. This would allow the logged in user ...