Doing this with a "condition" would be simple enough, but the 9C series just doesn't have this capability. You would need to go with at least an old 9Z or a current 12FG, 12Z or 14MZ transmitter.
I am sorry the radio you have is just not capable of this type of mix.
Sincerely,
Krysta
Product Development & Support Specialist
Futaba Service Center USA
[email protected]