007 - Replace and Attack

Sometimes when you've crossed hands, instead of using a pak sau to blow down their defense and make an opening for your punch to enter, you can instead place the pack sau on their arm to replace the force and not give them the signal that you're moving. Think Indian Jones replacing the golden idol with a bag of sand. They apply pressure, and you just sneakily transfer that pressure to your other hand, freeing your primary hand to attack or maneuver.