MIDI Pipe-Mac MIDI OX - PC Both are free Virtual MIDI routers that have been successfully used to add more than 1 MIDI controller... On a PC you'll need to create a port with LoopMIDI and additionally add Apple Bonjour for windows which includes Apple Talk for using a wireless Apple device to control from a 3rd party app aside from SXs app...
Lighting up the pads on a controller is already possible if your using an updated version of V7 Show Express unless your controller requires velocity to do it... however until Device IDs are recognised by Show Xpress/Sweetlight lighting up multiple controllers is not currently possible that I am aware of...
which "MIDI pads" are you using? I am using 2 Novation launchpads and MIDI Designer app on iPad