Backbone JS complex model fetch

I have two backbone models, loaded from server:

var Model = Backbone.Model.extend({});
var SubModel = Backbone.Model.extend({});

var SubCollection = Backbone.Collection.extend({
    model: SubModel
});

var m = new Model();
m.fetch({success: function(model)
{
    model.submodels = new SubCollection();
    model.submodels.url = "/sub/" + model.get("id");
    model.submodels.fetch();
}});

So, the server has to send two separate responses. For example:

{ name: "Model1", id: 1 } // For Model fetch

and

[{ name: "Submodel1", id: 1 }, { name: "Submodel2", id: 2 }] // For Submodel collection fetch

Is there a way to fetch a Model instance with Submodel collection at once, like:

{ 
  name: "Model1", 
  id: 1, 
  submodels: [{ name: "Submodel1", id: 2 }, { name: "Submodel1", id: 2 }]
}