An example showing how to create a through relationship, demonstrated with countries, regions, cities, and landmarks.
I wrote more about this in a blog post, Modelling through relationships with Ash
$ git clone git@github.com:sevenseacat/ash_through_relationship_example.git
$ cd ash_through_relationship_example
$ mix deps.get
$ mix ash.setup
$ mix run priv/repo/seeds/*.exs
Then you can test queries in iex, eg:
iex(1) Ash.get!(Example.World.Country, %{name: "Australia"}, load: [:city_count])