I’m not using different song states in a song but afaik song states can control midi routings (f.e. activate / deactivate a route). That said it should be easy to split your incoming midi-data into several streams using fix midi-filters in them.
This way you could have 4 routes f.e.:
- any information but cc64 for the organ
- any information but cc64 for brass
- only cc64 for organ
- only cc64 for brass
States should now be able to control any routing individually.
Hope I got your issue,