Creating a base route which will load the additional controller to the route.

gistfile1.txt

"use strict";

App.BaseRoute = Ember.Route.extend({
  renderTemplate: function () {
    this._super();
    this.loadAdditionalControllers();
  }
  ,loadAdditionalControllers: function(){
    this.render('flash',{
      controller: 'flash'
      ,outlet: 'flash'
    });
  }
});