Casio CZ/ VZ/ FZ - Pro Series

PS: Check out the Sysex guide in the files section, esp. p 3.

It shows an example with 2 synths:
Track 1 --> CH 1  [polyphonic synth]
Track 2 --> CH 2 VO 2 [CZ-101/1000]
Track 3 --> CH 2 VO 3 [CZ-101/1000]
Track 4 --> CH 2 VO 4 [CZ-101/1000]

So I would assume to get all 4 channels going to the CZ-101 you are 
doing the right thing.

Maybe someone else can help.