Generate each part individually and you should be able to select whichever substyle it is. At least for realtracks.

For MIDI I wonder if changing the prototype would help. In the style selection window hover over the prototype button and see what is displayed in top title bar compared to selected style. I've not tinkered with that much yet, so you may be leading the way for us.

I do not work here, but the benefits are still awesome
Make your sound your own!