After I create a macro, it cannot be used multiple times in another macro. Can macros be hierarchical?
Create a new design; copy, place, and route the sub-macros in the new design. Then, store the design as a macro. This new macro is not hierarchical, but it can be copied into a higher-level design.
Unfortunately, any changes to the low-level macro will not be seen in the higher-level macro, because the macro information is copied, not referenced.