If you just wish to show the other tales that are related to a specific table, you can show an endpoint (like orders or carts or patrons) and add /related to the url. eg:

https://127.0.0.1/api/v1/orders/related

Other Examples:

• https://127.0.0.1/api/v1/orders/related
  Relationships for orders
• https://127.0.0.1/api/v1/patrons/related
  Relationships for patrons
• https://127.0.0.1/api/v1/carts/related
  Relationships for all cart related items
• https://127.0.0.1/api/v1/orders/related?group=type+refers_to&agg=count&sort=-type
  Count of other tables that refer to orders by adding aggregate, sort and grouping functions