Drag follow parent entity

Hi all.

I’m trying this example, and I have a model and your son is an ellipse.

https://github.com/AnalyticalGraphicsInc/cesium/blob/master/Apps/Sandcastle/gallery/Show%20or%20Hide%20Entities.html

My question is, when I move (drag) the model (parent), is there any way for the son to follow the parent entity in the movement?

My solution was to add in the same entity the model and the ellipse but it works very slow.

thanks and regards

If use this sample

We can see hoy the ellipse move slowly.

Any hel for this