How would you achieve sub-masters in DL4?
I couldn't find this functionality but since it is such a common functionality I think I'm overlooking something.

I create my scenes with all dimmers on 100%. When doing a show I want to change the dimmer of each fixture family on the spot. The time, ambience, colour combination and fixture combination affect the desired dimmer position for that moment.
Switching a scene should not affect the dimmer output.
Thanks in advance!
- Sean