How do I share $scope data between states in angularjs ui-router?

Without using a service or constructing watchers in the parent controller, how would one give children states access to the main controller's $scope.

      .state("main", {
          controller:'mainController',
          url:"/main",
          templateUrl: "main_init.html"
      })  
      .state("main.1", {
          controller:'mainController',
          parent: 'main',
          url:"/1",
          templateUrl: 'form_1.html'
      })  
      .state("main.2", {
          controller:'mainController',
          parent: 'main',
          url: "/2",
          templateUrl: 'form_2.html'
      })  

I'm not able to access the mainController scope in child state--or rather I'm getting another instance of that scope--not what I want. I feel I'm missing something simple. There is a shared data config option in the state object but I'm not sure if this should be used for something like this.