I'm not sure in what way you want to "add" classifieds, however we do have another theme available called
ClassiPress which offers classified ad functionality. If you wanted to use both themes on the same site, you could potentially do this by installing them in subdirectories:
e.g.
yourdomain.com <== Your Vantage installation
yourdomain.com/classifieds <== Your ClassiPress installation
The themes cannot be used on the same instance of WordPress or integrated in the way that a plugin is. Thanks.
