Need to add additional features to the plugin

need to modify a plugin that allows me to add meta tags for my classified website category and i want to add some additional features to that plugin as said below.{i wil buy the plugin and you need to modify ) it should allow to add meta tags for city(subdomain activated) and region, for example <meta name="description" content="bitemango Delhi offers free picture uploading in Delhi. bitemango Delhi offers best free picture uploading for various categories like real estate, ."/> <meta name="keywords" content="picture uploading in Delhi, picture editing in Delhi, Delhi image editing software, best image edit software Delhi"/> <meta name="title" content="Free image editior in Delhi, free picture upload in Delhi, Online free image edit on bitemango"/> consider the above meta tags for example and it targets the delhi, th city name delhi should be replaced by the selected domain, if [login to view URL] then the delhi should be replaced by thanjavur. likewise it should update based on the city selected.