Have no idea why people brag over this.
You have upper lip controller right ? You have lower lip too ... What is sticky lips, can you define it?
So you have two controls right.Well your sticky lips slider can control a GROUP that is parent of both these controls.
If you control them with blendshapes similar thing.Have one controller for each upper and lower lip and another one that will control these two at the same time.
EUREKAAA, that is the complicated world of sticky lips
Cheers