Control Face through a Walk Cycle Animation

I have this walk cycle, it's frame by frame.  It's 8 frames I have on cycle layers.  I want to control his mouth/face while he's walking.  How would I do that? 

I added a mouth 8 different times onto each frame and tried to let the cycle layers play through but it doesn't work, it stops the cycle and goes back to my idle cycle.  Any info would help.  Thanks.