Your Linear system features a great Q and A presentation for local experts. Also, you can assign this feature to individual clients - who you may or may not list among your "Site" experts.
This easy interface will allow the Web visitor to submit a question to your client. If answered and approved, both the question and answer move back to the Web site. Email notifications keep the client on top of any new submissions.
The Q and A interface is fully searchable. the Questions are listed in descending chronological order so visitors can easily see when their question has been answered.