Creating Sitemap for Entire Domains install

Not sure if this is the place for this question, but here goes. At our school we use a web governance service called SiteImprove to help analyze all of the college associated websites. This is supposed to include every page created through our institutional account with Reclaim ( To make this happen, I believe I need to create a sitemap for the entire installation. I’m thinking I need to add a plugin like XML Sitemap Generator to the main site to create that. But that doesn’t seem to capture all the subdomains of the installation, but only the few pages that are directly within itself. I’m noodling around trying to figure this out, so thought I’d throw a call out for help … thanks.