Hierachical lists dependant on time and version?


I have an organizational structure based of 4 hiearchical lists (Division, Business area, Department and Cost center).
What is the best way to handle organizational changes if you want to be able to keep the old structure for previous versions/years but use a new structure for future versions/years?
Changes may occur on all levels of the hierarchy.

Thanks a lot for sharing your ideas!
Best, Lisa