I just found out you can do this so thought I’d share in case you didint know.
In session view if you hold shift and click on the buses you want you can then move the silders all at time but at different levels.
Means if you dont want to group and still want to have a layerd sound and control the overall vol this is a easy way to do it.
You may or may not know this but I didnt and think is handy so thats my tip for the day. 
you should post that for the ipad comp…