How do you report on multiple purchasing hierarchies?

Summary:

The Client has been live for years and has purchasing categories setup in Manage Functional Area Catalogs and then has a hierarchy setup under Manage Procurement Category Hierarchy. However they want to drastically change their categories and hierarchy. I believe reports are based on the category hierarchy (as you cannot setup a purchasing catalog with a hierarchy) so how do we report on both hierarchies? Do we have to simply create the new hierarchy and then embed the old hierarchy into it?

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