Group Members
You can create as many groups as you need but expect to enforce the rule that each user machine can only send audit data to one group account on the server machine. You can install as many group clients as required, groups can even have 100s of users.
A group of monitored users is overseen by the group Monitoring person, this will be the person who created the group. They can login and view the listed audit information for group users. Depending on the size of you network one or more groups will exist.