Tracking vistis across a website and a Recharge Checkout

General questions
1

HI Everyone,

I’m trying to consistently track a user across 2 domains one is a shopify site (lets call it myshop.com) but it has a recharge checkout on a different domain https://checkout.rechargeapps.com/

My question is, do i put this on recharge;

_paq.push(["setCookieDomain", "*.checkout.rechargeapps.com"]);
_paq.push(["setDomains",["*.myshop.com","*.checkout.rechargeapps.com"]]);
_paq.push(["enableCrossDomainLinking"]);

and this on myshop.com

_paq.push(["setCookieDomain", "*.myshop.com"]);
_paq.push(["setDomains",["*.myshop.com","*.checkout.rechargeapps.com"]]);
_paq.push(["enableCrossDomainLinking"]);

Thanks and sorry for the daft question,
Steve