need to make a subdomain on a domain mapped site

I have a multisite installed on llbh.com. I have a subdomain "drunkdriving.llbh.com" which we are going to use the domain mapping plugin to make it just "drunkdriving.com". My question is if I need this plugin or if I can just use the domain mapping plugin to make another site with a different theme at "directory.drunkdriving.com"

Thanks