Override the default content in ion-nav-view in child states

I create a state and its page with ion-nav-view(name=‘parent’) and then create a child state to override the content of the view.
I noticed if I specify any default content in the page by adding ion-view, the navigation to child state will fail.

It appears ion-nav-view does not support state hierarchy.

Thanks
Yuhang.

can you provide a codepen