I would like to address what I think is a fundamental misunderstanding of what the scenes on the SQ can bring to this problem. A scene on this mixer can capture every setting on the entire console. By properly using filters one scene can recall the setting for all 10 IEM mixes at one time, and not change anything else.
Do a run-through of your set at rehearsal, and have the FOH operator grab a scene at the end of every song. Have them filter for just the in-ear mixes that need to change. This can be accomplished easily with five scenes, even for all 10 people. As you said, ” The SQ possesses all the power needed to accomplish this.” No app update is needed.
You can even trigger these scenes from a small MIDI controller on stage or Ableton if you are using it for playback.
If this still doesn’t meet your needs I would suggest the addition of a monitor board on stage, and a dedicated volunteer to manage all that you are asking. To my knowledge, no manufacturer, has what you are asking for from an app, you would have to look to a third party to accomplish this.
