I wanted to call this out: We solved the first problem through a separate tool, which labels the user with the originating source when registering. Yes, yes, yes, and yes. If you're spending any significant amount of money on advertising, you need to be doing this. Don't rely solely on third-party cookies and session unification attempts. If you have a USER table in your database/crm, add the five UTM fields to it! C…
Aside from being more correct, as you don't duplicate this information with every session, you can update your "UTM parameters" at any time (keeping a history table, naturally) and avoid enormous and growing sets of rules to map previous structures to the newest one.