Ember Data: Saving relationships

I need to save a deep object to the server all at once and haven't been able to find any examples online that use the latest ember data (1.0.0-beta.4).

For example, with these models: (jsfiddle)

App.Child = DS.Model.extend({
    name: DS.attr('string'),
    age: DS.attr('number'),
    toys: DS.hasMany('toy', {async:true, embedded:'always'}),
});
App.Toy = DS.Model.extend({
    name: DS.attr('string'),
    child: DS.belongsTo('child')
});

And this code:

actions: {
    save: function(){
        var store = this.get('store'),
            child, toy;

        child = store.createRecord('child', {
            name: 'Herbert'
        });
        toy = store.createRecord('toy', {
            name: 'Kazoo'
        });

        child.set('toys', [toy]);
        child.save();
    }
}  

It only saves the JSON for the child object but not any of the toys -- not even side loaded:

{
  child: {
    age: null
    name: "Herbert"
  }
}

Do I have to manually save the toys too? Is there anyway that I can have it send the following JSON to the server:

{
  child: {
    age: null
    name: "Herbert",
    toys: [{
        name: "Kazoo"
    }]
  }
}

Or

{
  child: {
    age: null
    name: "Herbert",
    toys: [1]
  }
}

See JSFiddle: http://jsfiddle.net/jgillick/LNXyp/2/