My guess is no. The set includes one "master" plus two "slaves" that can plug into the master. It appears you can plug extra "slaves" into the first chain, and I expect that is what you have done to get five grouped together. The problem then is that you can NOT plug the second "master" into that chain. Without some digging for info and custom re-wiring of that second master unit, your best way to use it is as you have done already - by itself.
Now, you have no way to alter the display on that single one because you already have the first chain connected to your only case Reset switch cable. For the second "master" by itself, it will have a connector that is not in use right now with two contacts in it. The case Reset switch that is supposed to connect to is a simple momentary-contact normally-open switch. Same as a plain doorbell pushbutton. You could get any small switch like that and connect it to those two contacts. That would let you change the display on that last fan any time you want.