You don't want to change $network, you want to use something else to identify the different connection. Changing $network would break scripts that rely on identifying the actual network.
Sounds to me like you should probably script your own separate notify list, which wouldn't be hard at all using ON NOTIFY and ON UNOTIFY. You can add a "note" field to the user added in the notify list, so you can use that field to identify which user you want it to display in, and then create separate @windows to display the info.
