Adding and Removing Users on multiple servers

I know some communities have this but i have not been able to track down how it’s done. Basically when a user is added to a specific ulx user group on one server, it adds them to the group in all the servers. Same for when removing.

Is there an addon for this or is there a ULX file i can add the obviously-need database info into?

This is most likely done through an MYsql server.

Imagine 3 servers Admin’s Database is shared.

1 Database, connected with 3 servers. Shared information.