Many to Many field with a context field which is another relation?

Summary I have collections: cities (id, name) routes (id, name) routeCityStops (id, routeId, cityId, address, departureTime) routeFares (routeId, cityFromId, cityToId, priceValue) What is the best way to show in routes item details all routeFares belonging to this route as a table with ability to add/modify routeFare records? Many2Many did not help me because routeFares has 3 relations (because of cityFromId, cityToId and routeId). How to properly configure such setup for model with Route and RouteFares? Motivation Need to support "tripple" relationship like for routeCityStops in: cities (id, name) routes (id, name) routeCityStops (id, routeId, cityId, address, departureTime) routeFares (routeId, cityFromId, cityToId, priceValue) Requirements List Basically I want: 1. being on route item details page to see all routeFares related to this route with cityFrom, cityTo and price values 2. when new routeFares record is added from routes item …