Ugh, yeah, you're right, too bad a fader can't be removed from the totem logic....
This newbie to digital isn't using the Ipad app at this point, but I have set up my monitor mixes. There are a total of 14 MIX outputs, so my logic was to assign a mono MIX to each vocalist. Once I created that mix I added other vocalists or instruments as needed by the performer. Once the groups/MIX was created it was only a matter of pressing the MIX button and adjusting levels as needed.
What has turned out to be a benefit is that pressing the MIX button moves you to the mix and away from the main faders making changes fast and accurate even without label.
Create 4 monitor mixes using MIX 1 through 4.
MIX 1 - Assign lead vocalist and backup singers to output.
Adjust levels as needed