Cross domain tracking and preserving cookie

Is there a guide to configuring cross domain tracking with the Snowplow JS tracker?

I can see in the technical document for the tracker (here) how to set the cookie domain to span multiple sub-domains, but I don’t see any reference to adding multiple domains.

Also in the same doc (here) how to set up auto-linking (to use GA’s terminology) to pass the domain users ID onto the landing page of the new domain.

As far as I follow, as long as we add and into the cookie domain argument, and auto-decorate all links from one site to the other this should work as expected? Thus, preserving session information, session indexes, original referrer info etc.?

Or, is there a further step in data modelling to manually stitch sessions together, looking for where the referring domain is one of the domains, and the page has the _sp parameter in the URL?