Edit in JSFiddle

<div ng-controller="MainCtrl">
    {{greet}}!! {{whoami}}
    <div ng-controller="NavCtrl">
        {{greet}}!! {{whoami}}
    </div>
    <div ng-controller="SideCtrl">
        {{greet}}!! {{whoami}}
    </div>
</div>
function ParentCtrl($scope) {
    $scope.greet = "Hello";
}

function MainCtrl($scope) {
    angular.extend(this, new ParentCtrl($scope));
    $scope.whoami= "Main Controller";
}

function NavCtrl($scope) {
    angular.extend(this, new ParentCtrl($scope));
    $scope.whoami= "Nav Controller";
}

function SideCtrl($scope) {
    angular.extend(this, new ParentCtrl($scope));
    $scope.whoami= "Side Controller";
}