I apologize, I was not very clear on the topic. Eric, what you're describing is a second "automation lane". But I don't need an additional automation. What I want is to simulate the automation trim field, increasing or decreasing the overall level of existing automation with the mixer fader.
In usual project you have some tracks with the volume automation and some without. Instead of just adjusting mixer fader you have to open automation, check if some automation is existing and if yes, use the trim field to adjust the overall volume level. Kind of cumbersome workflow for me.