Although I've been offline for some time, I've explained in older messages that I use several custom columns (
#universe; #ser1, #ser2, etc) to produce something similar.
#universe is the largest "bucket" for grouping books together from one or more authors and/or series. It is meant to be a location name wherein all events from all books take place. Particularly helpful if they're prolific writers and/or have several separate series that are later declared to be in the same over-all setting.
#ser1 (etc) is a "nested" set of series columns. They're basically used in the standard Calibre manner, but sub-dividing series as needed. This works, for instance, to place books into time groups (Medieval, Renaissance, etc), characters (Doctor Who [a time traveler so time groups are useless here!]), multi-generational writings, etc. The nesting is important here because it means that entry is a container that partially or wholly holds other sub-series.
Thereafter I've standardized the index numbers used to account for oddities. I won't try giving examples here.
Anyway, it's not perfect. I still have not found a good way to account for cross-over books (example: Superman vs X-Men both having separate and complex series numbers of their own, etc).