Click the "Share Group" option for the group you wish to manage.
Click on the chekbox next to the username (e.g. \\aon\john) to share the group with a single user or next to the domain name (e.g. aon) to share the group with all users in domain.
Important: The administrator of ISL Conference Proxy can set which users and domains you can see in the Share Group dialog window. For privacy reasons you will not be able to see any other user until the administrator enables this option in ISL Conference Proxy settings. The following settings have to be changed: User can view list of domains on server , User can view list of users in own domain and User can view list of users on server. They are described here: Security.
Select the Permissons for the user you selected in Step 2 and click "Save".
Step 3.1 (Optional)
You will get a warning if you decide to lower your group permissions as you won't be able to revert the change afterwards - Only Group Admins can do so.
Step 3.2 (Optional)
You won't be able to change user and group settings if you are not a Group Admin.