Thank you John! After spending some time fiddling with it I started to realize this, thanks for confirming it here.
I manage to achieve what I want by setting custom HTTP headers on the two domains within Cloudflare; “tagging” all the traffic for the specific domains. Then it was just a matter of creating a few Redirection rules that use the “URL and HTTP header” matching mode, and voilá.
Works perfectly so far!
Also, I use Cloudflare for all my domains
