Maya (2013+) - imagePlane issue

I had trouble with imagePlane in maya 2015. As far as I know it is changed around maya 2013. ImagePlane now has a transform node so it looks like a standard object. You can create it from the menu: Create / Free Image Plane.

The strange thing is that when it is attached to a camera. It looks like a hierarchy (see below)

but it can't be unparent or reparent. So there is a special connection. In nodeEditor it also looks like a typical hierarchy where the transform node does not have any connection.

Only thing which can refer to some special condition is found in the scriptEditor when the imagePlane is selected:

select -r CameraShape->imagePlane1 ;

I experienced this syntax with positionMarkers. Actually I wrote about it before.

That is how I find out there is a term of underworld nodes in maya. You can read about it here or a more here. Consider underworld node as a component like a NURBS CV and it will explain why it can't be unparented for eg.

So...we can create an imagePlane with MEL command (since maya 2013) like this:

imagePlane -name "myImagePlane" -camera "CameraShape";

And we can redirect" an existing imagePlane to another camera with the edit flag:

imagePlane -edit -camera "NewCameraShape" "myImagePlane";

I found the easiest way to get the imagePlane from the camera is to call this:

listRelatives -allDescendents "cameraShape"