Tourist,
However you wish to define "Derivative" is your business.
That the V-22 is directly based upon research done on the XV-3, XV-15, and projects done to overcome problems with the design of Tilt Rotor Aircraft is not debatable as it most assuredly is.
If we can say the UH-1 Huey is derived from the Bell 47, we can most assuredly say the same about the Osprey and its roots in the XV-3.
That History started in 1950 with the first flight taking place in 1955.
http://history.nasa.gov/monograph17.pdf