We use squarespace and shopify together as they are both great at certains aspects but are lacking in others. Squarespace is relatively easy to use and build sites but it makes it much more challenging to build SEO strategies for two domains. I hear SP is stepping up their game when it comes to ecommerce so we may move everything over to Squarespace. bodyflowhydration.com is currently runs SP for the front end and Shopify for the product purchases. Not ideal.