In a previous post, I added a related site as a subdomain. I had before configured Google Analytics for the main site, but I didn’t know if I could simply add the same measurement ID to this new site.

Google Analytics 4 allows cross-domain measurement, unifying the measurement of users and sessions within a single data stream. The setup is explained in this video.

I use Contains match type, with domain in the cross-domain linking configuration. This way www, paths, and any other subdomain I will add in the future are included. The same measurement ID is applied to all subdomains.

If in the future I add a new domain that should also be tracked together, or if I add a new subdomain that doesn’t need to be tracked, then I will review this configuration.