As a sort of addendum to Dustins suggestion concerning the DCA master placement, which I think is a very valid one (-> https://community.allen-heath.com/forums/topic/dca-spill-fader-placement?fbclid=IwAR1sJEyGVo__lxn5QWscQtHvUtyHVhgmny7e_ErTgH8MY1kPebZW3m-syc4), I would like to suggest to make a DCA master that is in spill mode more visible.
The slow blinking Mix button just isn’t very intuitive and forces you to actively look at the console for a second to see if a spill is active or not, especially so, if DCAs are packed and therefor the fader strips are populated (almost) entirely, even in spill mode.
I would suggest the Mix button blinking faster or just be constantly lit (maybe with a short, inverse blinking sequence, so it doesn’t look too busy). In addition, the scribble strip display of the spilled master DCA could change between the name of the DCA and “spill”.
Last but not least, an indicator at the bottom of the screen (like when a “listen” function or VSC is active) would be great.
Between all those indicators, it would be easy to have a “feel” if what we are looking it are layers or a spilled DCA.