Is there any way to Extend SimpleRenderable,SceneManager class in MOgre 1.6.2?
You mean from C#, right ?
It is not possible with Mogre 1.6.2, and I'm not sure if it will ever be; it requires a lot of work.
A less general way may be easier. I mean writing a custom C++/CLI class to allow "subclassing" of SimpleRenderable; do you have a use case in mind ?[/edit]