creating sub-server

I need to be able to allow one domain administrator the ability to add sub-servers themselves. She wants to register domain names for her real estate clients, and set up a website for the individual owner until the house sells, and then remove it. Right now, things are set up in such a way that I would have to add the domains as the system administrator. Is there a way for me to give just that one top-level server the ability to add sub-servers themselves?