I typically refer to this scenario in the context of a Primary hierarchy and one or more Alternate Hierarchies.
Generally, some amount of data collection / data editing takes place in one hierarchy, but needs to be reported in some other hierarchy. Basic stuff, right?
A simple example is with a Staffing Plan... the primary hierarchy might be department/organization based, but an alternate summary might be, say, by location (with location being an attribute of employee, or the employee's department, etc).
Another example might be a composite hierarchy that gathers data by, say, Entity & Function, but you need to switch the rollup to be Function & Entity... In this case, we can usually have an automated/button process that an admin periodically presses to create the Function-Entity hierarchy, and the related Function-Entity module sums data from the Entity-Function input module via a dynamic mapping (in the source module).