Yes, it is possible to achieve the desired scenario - you can create a UserControl, place a RadDock control in it, and place the UserControl in a ToolWindow of another RadDock. Further, you can pull out ToolWindows out of the RadDock placed in the UserControl, and these ToolWindows will become separate Forms. To make sure that we are on the same page, I want to clarify that the ToolWindows will become separate forms, but they will still be a part of the application, i.e. if you close the main form of the application, the dragged ToolWindows (that have become forms) will be closed as well. This is a standard .NET behavior. Moreover, you can't dock the ToolWindows from the inner RadDock to the outer RadDock and vice versa.
I hope that this explanation helps. Let me know if you have additional questions.
the Telerik team