Now in the xml files the position and rotation of a part is stored under the Part tag. We can add multiple fuselages, wheels, cabins... whatever into the same part but they have to share rotation and position.
Having a position and rotation displacement under Fuselage would let us make complex looking parts that behave like just one craft. This could be implemented in absolute values (having the position inside the fuselage tag) or relative (having the displacement relative to the part position/rotation.