Unless something has changed recently without an announcement, to use multiple Shopify stores you must have separate Shopify accounts. We asked them about this when they first added Locations and they didn't seem very interested. I find it rather odd since they say Use one platform to sell products to anyone, anywhere—online with your ecommerce store, online marketplaces, and social media, and in-person with point of sale. on the front of Shopify.com. You can have multiple physical locations under one account, but not multiple online locations. Very frustrating.