Thanks, Roger, but I've tried every possible combination--simutaneous, A before B, B before A, different holding times, etc.
Mike, I got suceeded with your directions. However, the layered tones that I want to tweek are the combination of the piano tone that comes on when you first turn on the keyboard, and the strings tone that comes on when you first press the strings button. Are these two tones somewhere in the User Preset collection, as well as in the Built-In Tones collection? If not, I can probably make do with one of the User Preset substitues, but those Built-In tones are really to my liking. To my knowledge, Tech support didn't call me today, but you've been very helpful. Thanks to you and all who reached out.