How To Enable User-Defined Hierarchies in SQL Server Analysis Services

Problem
I have a requirement to provide users with the capability to define their own reporting hierarchies for sales data. For instance they had a report which broke down sales by the four regional VPs then by office.  Later they created regions, assigned VPs to each region, then assigned offices to each VP.  Now they want to be able to create a number of other scenarios and choose which one when they run a report.  Can you provide some suggestions on how to do this? 

Solution
There is a relatively simple solution to your problem that leverages the many-to-many dimension capability in an SSAS cube.  Let's start out with a simple dimensional model then expand upon it to allow multiple reporting hierarchies.