Why does this group need to be restricted ?
If it is because only those in the group need it, then they should have it in their personal NABs, and it could be removed from the server. If some secretaries or employees still need without being part of it, then they could also have it in their own NABs. Of course, this always entails the hassle of updating.
If it is because some people using a database need it, then the group could be inserted into that database, instead of the server NAB. Thus, a button could be made, available only to the certified users, that would create a memo with the group in it already expanded. All users who would need to access the button would just need to be part of the role allowing it, and would not necessarily need to be in the actual group.
Now, taking a step back : since all users who can get mail via Notes have a valid address, and since all Groups in the NAB contain Notes addresses, what is to prevent a user from putting all the people in this "special" group in a SendTo and send it ?
Sure, they'll have to do it manually, but no one can keep them from doing so. A group is just a facilitator, it is not a security device.
Think about that.
Pascal.