We have a set of custom site definitions, around 12 in total, that makes up a large sharepoint 2010 intranet application (circa 40,000 sub-sites) that has been deployed for a few years now.
One of these site definitions now needs some tweaks. Namely, a new page adding to it with some pre-configured web parts, and inserting a new web part into the landing page.
I understand I can create a new feature for this update, and associate it with the site definition in question, and that's all fine for new sites being provisioned from this site definition, but how do I go about applying the same changes to the existing 40,000 sites, which also need the update?
Thanks for any assistance, Tony