I know there's a plugin called Multisite User Management, but this simply adds a new user to all sites in a network. What i'm trying to do is a bit more complicated:
I have 5 sites in a network: Site 1, the main one, then 2, 3, 4, and 5. When a user is added to 2, 3, or 4, I want them to also be added to 1 automatically. When their role changes on 2, 3, or 4, I want their role to change on 1. When users are added to 5 it has no effect on the other sites.
Is there a way to do this? 2, 3, and 4 stay in sync with 1, but not with 5, or with each other.