You shouldn't have to add anything manually. I believe you can just open the Search behaviour that is already applied by double clicking on it from in the Server behaviours panel and add the extra criteria there.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.