How to create a second Driver to Same Bone?

Support Animation and Rigging
1

I have baked a sound to an f-curve on an empty, then made a driver for a jaw bone. Works well.

How can I then bake a new sound to the empty and create a driver for the same bone? When I try to create the second driver (same x axis), there is no place to add the driver; and you cannot add to the keying set.

The reason for more drivers is I want to continue adding more dialog to a character.

Thanks for your attention.

Blender 278c