Multi-disc DiscSubtitle sorting

[jake.t]

discsubtitle and discnumber seem to work for all compilations quite well but I've come across my first set that doesn't. 30 trips around the sun from Grateful dead unless I flatten discs to Dxx then use discsubtitle

its Album, then city of date (like Providence, RI), then any range of discs from 1 to 3 for that date. If I use real discnumber its a mess.

I think albumsubtitle grouping would work here, did this ever get implemented as suggested?