How do you set an attribute to the join resource when creating?

create :create do
  accept [:name]
  argument :user_id, :binary

  change fn changeset, %{actor: actor} = _context ->
    changeset |> Ash.Changeset.set_argument(:user_id, actor.id)
  end

  change manage_relationship(:user_id, :users, type: :append_and_remove)
  # ^^^ somehow set :role to :owner in this relationship
end