What I ended up using after smacking my face against backbone relational and backbone associations

gistfile1.js

//= require ../collections/children.js
(function($){
  demo.models.Parent = Backbone.Model.extend({
    initialize: function(options) {
      this.children = new demo.collections.Children();
      this.attributes = this.parse(this.attributes);
    }

    , exampleJSON: {
      someAttr: 'some value'
      , children: [
        { content: "valid contents for other model"}
        , { content: "more valid contents for other model"}
      ]
    }

    // override parse and toJSON to handle children as a collection
    , parse: function(json){
      if (this.children) {
        json.modified = false;
        this.children.reset(json.children);
        delete json.children;
      }

      return json;
    }

    , toJSON: function(){
      var json = Backbone.Model.prototype.toJSON.apply(this);
      json.children = this.children.toJSON();

      return json;
    }
  });
}(jQuery));