Hi,

If you are using 1 installation of Kentico CMS to manage all these live sites, you could take an advantage of the option Site name in Properties of your search web part. You could use for example 3 Search results web parts each with another Site name. This would find the results of the first site, below them the results of second site and so on.

Or there is a possibility to clone and re-write the standard search web parts (your_project_folder/CMSWebParts/Search/*). More information about this could be found here: http://devnet.kentico.com/docs/devguide/modifying_the_design_of_standa.htm

You could also develop your own search provider (http://devnet.kentico.com/docs/devguide/development_of_a_custom_search.htm).

Best regards,
Helena Grulichova