Which UTM arguments do apply in a multi site setup?

Question

I have two sites (Site A and Site B) on two domains. On both sites the same GA tracking code is set up and on Site A the "linker" is enabled for multi site tracking as explained here.

Site A is a landing page while Site B is the page where the product can be bought.

If a user enters Site A on

https://siteA.com?utm_campaign=foo&utm_source=3rdparty

and clicks a link on Site B with

https://siteB.com?utm_campaign=bar&utm_source=siteA

Will the utm_campaign on the checkout always be "bar" or will it be "foo"?

Do I have to remove the utm_* on the link on Site A to preserve "foo" or do I have to rewrite the parameters to keep them?

It should be "foo" if the user is coming from the "3rdparty" and "bar" otherwise.

Answer 1

In your scenario 'utm_campaign' will be bar.

However in cross-domain monitoring **you don't have to use *utm_****, otherwise it doesn't make sense to talk about cross-domain tracking.

Every time you move from one site to another through the utm, you stop the current session and generate a new one... while the purpose of cross-domain tracking is to understand how the same session moves between the two sites.

Answer 2

You will see both - "foo" and "bar" - in GA reports, but only "bar" on the checkout because of any new value of utm parameter starts the new session.

In case of cross-domain tracking is set up correctly, to see full path of user from Site A to Site B you should use utm only once: for landing page of Site A.