I run a website across 6 shopify stores - they all share the same domain but are hosted on different subdomains. The stores are identical except for stock (they have separate warehouses), pricing and delivery costs/times. all links go to one main store at which point a pop up comes up and the customer is asked which store they which to visit (and sent to that store). All accounts are set up on the main store so when a customer logs in they are sent to the main store to log in and then sent back to the store they were on originally.
They are linked to the same google analytics account and are set up in online store -> preferences (rather than in GTM or directly in the code).
I've added each subdomain into the referral exclusion list. I'm still getting a new session every time I move between stores greatly inflating my session number and decreasing my Conversion rate (shown with google tag assistant). I've read about the google linker plugin but I'm unsure how to get that working in Shopify. It would be fantastic if there was a solution. Thanks in advance!