Since you are committed to User control and privacy, while Administrators are concerned about completeness and accuracy, would you consider implementing a method that would allow Administrators to add information update requests to users, where the Administrator ends the proposed update and this sends a link to the user to allow them to view and approve the change/update? The big issue with homeowners is that they lack motivation to update material on their own. This sort of extra push would make it as simple as possible to prod them to do it, by mostly doing it for them.