You need to go to the IO set up to the D Snake in tab.
the 2412 will be set up at least to start one to one, main 1 to channel 1 and on to
channel 24.
The AB168 in the expander port will be set with main 1 to channel 25 and on to channel 32.
Then you need to go the pre amp input set up screen and switch the needed inputs from local to D Snake, red to yellow.
In the IO set up menu is where you can assign any input on a stage box to be any channel on the mixer or a single stage box input could feed multiple channels on the mixer.
All the IO settings are saved as part of a scene.
I find the iPad Mix Pad APP the IO set up menu easier to use as is shows the routing in a matrix style grid.
Also remember if you need to squeeze in a couple more mic channel using a stage box you
can assign a stage box mic input to a stereo input on a QU.