It's actually really flexible as you can something belong to multiple groups at the same time - I think you can get "most" of the way there with groups and busses in SONAR. VCA technology is the standard grouping methodology in high end desks.
Let's see taking the OP's original requirements - he could:
Put all of library 1 on buss A
Put all of library 2 on buss B
Group Violins together
Group Violas together
Group Cellos together
Groups Basses together
I actually think that covers it per his original request.