You can use up to 3 S16 snakes and use a total of 48, but you will only have access to 32 inputs at a time via the X32 panel. To view this, go to the HOME tab within the ROUTING page. You may select each of the 1-48 inputs via AES50, but will only have 4 banks of 8 (total 32) to do this with. A situation for this application would be having 3 snakes on stage (one far left, one center, and one far right) in which you would assign these limited banks of 8 to split between the three S16s. You could have all inputs on the center S16 active, and only inputs 1-8 active on the left and right S16s. Then you can change all of these assignments at the X32 (if need be) without unplugging any of the AES50 (Cat5e) cables.
Keywords: X32- What Is The Maximum Number Of Inputs For An X32 With S16 Digital Snakes?