What you are looking for are Linked product variations/ Combined listings. If you are on a Plus plan, Shopify has a specific app for it: https://help.shopify.com/en/manual/products/combined-listings  Otherwise, depending on the theme you are using, i...

This is fake. If Shopify contacts you, it won't be through a Gmail email, but an official Shopify email (something@shopify.com).