In your MFC application, you could try to find the main window handle of the Orbiter process, then use SetParent() to put it inside you application's window. I'm not sure if it works with D3D9Client, but it should for standard Orbiter.
It would be a hack, though. It would mean that you have to be careful with all window messaging passing into that window, as well as with operations that resize the parent window.
Why do you want this? Can you elaborate a bit on the goal you are pursuing with all of this? I hope it is not to simply exchange the frame and pass it along as "My Space Sim" or somesuch.