Define which administrator roles are to be available in extranet spaces.
These have all of the permissions that the normal space administrators have. Additionally they can use all of the extranet features within their extranet.
An Extranet Space Manager can see all users in the system. Make sure that this is allowed when you assign an external user as an Extranet Space Manager.
Users assigned to this role can use all of the extranet features within their extranet space. However, they are not a space administrator like the Extranet Space manager, and therefore can not administor the spaces themselves. The Extranet User manager also can not assign groups to their Extranet Space.
In the default configuration, Extranet User Managers can see all users in the system. Make sure this is allowed when you assign an external user as an Extranet User Manager. You can limit which users the Extranet User Manager can see with the option "Extranet user administrators are allowed to assign ..."
If you do limit user visibility for Extranet User Managers with this option, the users that they can see will depend on whether they are an:
Internal Extranet User Manager
When an Extranet User Manager belongs to an internal group, they can see all users in the system and assign them to their extranet space.
External Extranet User Manager
External Extranet User Managers can only assign users to their space with whom they share another space. That means they can manage the users within their space without seeing all of the other users in the system.