Bill,
You can easily do this using the keyboard's onboard Song Creator program and the Mixing Console.
If you want I can give you a call and walk you through the process.
Gary

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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)