When you log in your gateway via ssh.You just log in one module.So,you will see only 4 spans .For example,your first module ip is 172.16.0.80,when you log in via ssh,you will see 4 spans.Your second module Ip is 172.16.0.81,When you log in,you will see 4 spans.4+4=8.
About the system.conf.The file is read-only file.So,you can't to edit it.
i'm sorry i read about the different ip of all modules when i first bougth the gateway, but i was waiting for some the sims for the second module to configure it, and in the mean time i forgot this information