Add boolean checkboxes ng-model to object AngularJS

I am trying to do something like tree-checkboxes. I would like to add boolean to children of checked name : ex. after click checkbox at name : eva - all her childrens will be also checked. Like that :

$scope.messages = 
    {

    "family": [

        {

            "name": "eva",
            "checked" : true,
            "childrens": [

                {

                    "name": "John",
                    "checked" : true,
                    "childrens": [

                        {

                            "name": "Jacob",
                            "checked" : true,
                        }

My code :

 <div ng-repeat="key in messages">
    <ul ng-repeat=" (x, y) in key" style="list-style:none;">
      <li>
        <input type="checkbox" ng-model="y.check" ng-change="changeValue(shapes, y.name)" />  </li>
      <li style="margin-left:15px;" ng-repeat="(a,b) in y.childrens">
        <input type="checkbox" ng-model="b.check" ng-change="changeValue(shapes, b.name)" />  
        <ul style="margin-left:15px;" ng-repeat="p in b.childrens">
          <li>
            <input type="checkbox" ng-model="p.check" ng-change="changeValue(shapes, p.name)" />  </li>
        </ul>
      </li>
    </ul>
  </div>

Here is my plnkr : http://plnkr.co/edit/lFYUvcTt1W709vam5Dfv?p=preview