How/when to query 'extended' entities in B

I have a ViewModel that loads up 'child' entities and I want to also display 'grandchild' entities based off of each child that is loaded. To simplify things, I need help identifying how to query these objects and display them under the proper 'tree' in the browser (apologies for my butchering of coding language : ))

I am using Knockout to bind the data and loading up the entities with Breeze. This question is an extension of When to add extend additional complex types onto a Breeze entity

Also - my model is EF code first and I have a configuration defining a one to many relationship between children and grandchildren, and I think Breeze knows this already but I am trying to figure out how to take advantage of this.

childs.js (view model)

var childs = ko.observableArray();
var grandChilds = ko.observableArray();
var parentId = ko.observable();

function refresh() {
    var parentId = (parent).parentId;  // << for ex. don't worry about this line : )
    return Q.all([getChildren(), getGrandChildren()]);
}

function getChildren() {
    return datacontext.getChildren(childs, parentId);
}

function getGrandChildren() {
    return datacontext.getGrandChildren(grandChilds);
}

and in the view (childs.html)

<div data-bind="foreach: childs">
    <div title="Go to Child Details">
        <div><strong data-bind="text: name"></strong></div>
        <div><strong data-bind="text: gender().description"></strong></div>
    </div>
    <div>
        <!-- ko.compose { view: grandChilds} --><!--/ko-->
    </div>
</div>

And my current datacontext for reference

    var getChilds= function (childsObservable, parentId) {

        var query = EntityQuery.from('Childs')
            .where('parentId', '==', parentId)
            .expand('grandChildren')
            .orderBy('id');

        return manager.executeQuery(query)
            .then(querySucceeded)
            .fail(queryFailed);

        function querySucceeded(data) {
            if (childsObservable) {
                childsObservable(data.results);
            }
            logger.log('Retrieved [Childs] and [Grandchilds] from remote data source', data, system.getModuleId(datacontext), true);
        }
    };

I want to load up only grandchildren of the children, and since there are many children I want to only display grandchildren under the correct child, not all grandchildren in one list. Any help would be appreciated.

You have three basic approaches to querying and "linking" related entities.

1) Use EntityQuery.expand

2) Use EntityAspect.loadNavigationProperty

3) Create a "broad" EntityQuery that just happens to encompass the entire graph and all of the parent/child relations will be automatically linked.