Z-Wave supports master, and slave controllers.
It is possible to have X amount of devices controlled by Z-Wave controller A, and Y amount of devices controlled by Z-Wave controller B. Then A+B can be tied together where one is master, the other is slave, and X+Y devices can be controlled all from the master controller.
I just do not know how to do that on HomeGenie, but I've seen posts from other people linking multiple HomeGenie controllers together.