The app will only ever see the main rack so only the first 64 channels and not the second rack or expander.
How many inputs in total are you using from both racks?
If it fits within 64 then is it not possible to just use say the first 32
from the idr10 for your wireless mics etc then set up inputs 33 upwards
so the input is patched from port B which is the second rack?
Should just be a whole bunch of input patching
If you use more than 64 inputs then just fit what he needs in his monitors
within the first 64….. Although I think 65 and up can only be sourced from the
second rack…
Save your channels in libraries and don’t forget to tick recall head amp gain
I’ve not used dual rack in ages but I think it should work that way….
I tend to use dante to fire stuff between racks but that limits you to 64
Channels anyway…
Good luck