Does anyone know of a way in XOOPS to implement basic hierarchical user management?

What I have is a private XOOPS site where registration is handled solely by the administrator. The users and groups of that site, although small in number at any given time, may be quite dynamic from time to time so need to be added and managed as required by someone other than the admin user.

I've discovered in XOOPS 2.2.2 that the ability to add, edit, delete and otherwise manage users and groups appears to be an all or nothing situation. If I go into admin>users>groups>modify for the selected group and check "Groups" in the "System Admin Rights" section, anyone in that group has the ability to delete any XOOPS user, including themselves and the admin users.

What I need is the ability to have one group, probably with only one member, who can add, edit and delete users and groups as needed for their purposes but NOT have the ability to change anything that is system critical. In other words, permission to do whatever they want to something at or below their permission level but cannot touch anything higher than their permission level.

I've searched through the XOOPS site but haven't been able to find anything relevant to this particular need. And of course there's that little voice in my head that keeps saying "It's such an obvious need, surely I must be missing something." But if I am, I must be blind.

So... any ideas or suggestions on how this situation might best be handled?

Thanks for your time.

jaquita