Use two columns in the fact table instead of having a geog table.
Apply Section Access as
User, Password, Geog_ID
RepA, Pass, A1
RepA, Pass, A12
Problem : You will end up rolling up your data at each geog level and multiple your records drastically. In an application in my experience we ended up rolling to the point where QV components started complaining about insufficient memory and the whole approach got scrapped.
Any body else have a better idea please let me know too.