<div ng-controller="ParentCtrl as parent">
   <div ng-controller="ChildOneCtrl as chi1"></div>
   <div ng-controller="ChildTwoCtrl as chi2"></div>
   <div ng-controller="ChildThreeCtrl as chi3"></div>
</div>

function ChildOneCtrl ($scope, sharedService) {

   var chi1 = this;

   sharedService.getChildOneData()
       .then(function (res) {
            $rootScope.$emit('childOneDataEmited', res.data);
       }).catch(function (err) {
           console.log(err);
       });
}

function ChildTwoCtrl ($scope, $rootScope, sharedService) {

   var chi2 = this;

   var onEmitChildOne = $rootScope.$on('childOneDataEmited', function (event, data) {
        getData(data);
   });

   $scope.$on('$destroy', onEmitChildOne);

   function getData(data){

       var chi1Data = data;

       if(chi1Data.uEnabled){
           sharedService.getChildTwoData()
              .then(function (res) {
                  $rootScope.$emit('childTwoDataEmited', res.data);
              }).catch(function (err) {
                 console.log(err);
              });
       }
   }
}

function ChildThreeCtrl ($scope, $rootScope, sharedService) {

   var chi3 = this;

   var onEmitChildThree = $rootScope.$on('childTwoDataEmited', function (event, data) {
        getData(data);
   });

   $scope.$on('$destroy', onEmitChildThree);

   function getData(data){

       var chi2Data = data;

       sharedService.getChildThreeData()
          .then(function (res) {
               //to do some data manipulation
               console.log(res)
               console.log(chi2Data)
          }).catch(function (err) {
              console.log(err);
          });
   }
}