Is there an app that adds this feature for customers themselves? Does Shopify Plus have this?
The only information I could find was for the store owner side, not the customer side. Currently, customers can add additional addresses in their address book one by one, but I am looking for a way to automate this.
It depends on what the end goal is and what it solves for your scenario. We are developing so added B2B functionality for our Shopify integration so would be interested to know what your roadblocks are.