delegation of permissions to group

Hi Everyone,

I have requirement where in I need to delegate the permission to group.

For ex: I have group called Testgrp and helpdesk users are the members of the group.

I want help desk users should be able to modify  "Member of" items, like add or remove from the member of list from user properties. However i want to restrict the helpdesk users to not modify group membership like users should not be able to add/remove user/groups to any group.

Kindly Advice

Thanks!!