I thought it would be possible and it was indeed. Set tracks that you want to group one below another. Create new track (maybe call it GROUPED) above the tracks you want to group volume for. Click on the folder icon (in my version it’s under the track order number on the right). Then click once or twice on the folder icon for the last track in the group. This will indent the tracks under the main GROUPED one. Now making the volume envelope visible will affect all tracks in that group. Cool.