Hello IAB,
Hierarchy is the master data so it does not have any impact on Infocube/Multiprovider. In infocube, the records are saved in as flat values.
You can definitely arrange one hierarchy according to your need or even you can copy existing hierarchy in RSH1 with another name and do the changes in the copied one.
If they have to be used in same report, you need to create a variable in the report so that user can select hierarchy accordiong to their need.
Cheers,
-Su