I have the following problem in ember.js. A child controller depends on a selected value in a parent controller in order to determine its content. In the database a child has a parent_id reference.

App.parentsController = Em.ArrayController.create({
    content: [],
    selected: null
});

App.sonsController = Em.ArrayController.create({
    // the value of content depends on the id of
    // the selected item in the parentsController
    content: [], 
    selected: null
});

App.daughtersController = Em.ArrayController.create({
    // the value of content depends on the id of
    // the selected item in the parentsController
    content: [], 
    selected: null
});

I would prefer to solve this without the parentsController having to know anything about the other controllers. This should be possible with observers, bindings or even through calculations but I have no clue where to start. Any help would be well appreciated.