Add a new user and assign it automatically to the group

Hi, I would first like to thank you for the great work, I think drupal has always needed such a useful module.

I would like to have a group manager who can administer all members in the group and can create/add a new users which will be assigned automatically to that group.

a use case would be: Company X sells access rights to company Y and company Z, X wants Y and Z to create and manage their own users without having to ask X to create the users for them.

Of course, the group manager should be able to administer the members of the group only, not the site global users.

Thank you again.