Hierarchical indexing of tags with multiple values?

[Uoppi]

I tried looking through the documentation, but I'm still not sure if it's possible to display the library index hierarchically, when a tag contains multiple values?

My usage scenario:
All my classical music is tagged "Classical; Chamber" etc. In other words, always with "Classical" first, followed by the subgenre (split by semicolon).

So when browsing the library in Android BubbleUPnP, I'd like the index levels to be filtered hierarchically like so:
1. level: Genre
2. level: Classical, Rock & pop, Jazz
3. level (The 2nd genre tag value, if Classical was chosen): Chamber, Orchestral, Piano etc.

This would de-clutter the genre index view significantly. I don't need to see all the classical subgenres when I'm intending to listen to rock. As it happens right now, I need to scroll down to make the "Rock & pop" genre visible.

I'm not sure if this can be somehow achieved using TagUpdate (but I suppose not)? Create a SubGenre tag by TagUpdate or something?