I think your requirement is doable, but may need a little bit of thought on getting it to work as you want, but a really good place to start to look at modules is at ventrian - http://www.ventrian.com whereby they have a property agent module.
There are different ways to bring sub agents into the picture - but I think even a simple page on the website using hidden tabs and roles for management would work.
But yes, from my 4 years of working with hundreds of dnn sites, I think it's doable, it depends on how you want to approach it.
Clever planning and exploring what modules will help you create something that's manageable and replicateable in the long term for your agent subsite.
I've worked on a couple of projects that are 'franchise based' and we were able to create some site that kept the 'global' or franchsor look and feel, but gave a level of independence for the franchisees, but were always under full management of the franchisor.
I hope this gives you an insight to what you can do and ventrian offers an excellent set of modules that will help you get started.
Nina Meiers
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If it's on DNN, I fix, build, deploy, support,skin, host, design, consult, implement, integrate and done since 2003.
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