Just an aside, #5 is nearly identical to how I teach working with over-extension to lead an attacker into a throw/takedown.Actually their are about half-a-dozen ways to "borrow" your opponent's force in the striking art of Wing Chun.
1. Collision Principle: slip or deflect the incoming punch with your counterpunch so your opponent's forward momentum adds his force to yours as he collides with your fist.
2. Pivot Principle: You receive the incoming force with one arm pivoting with the force and return it simultaneously punching with the other arm, as in tan-da sau with a turn.
3. Rebound Principle: You parry, rebounding off the incoming strike borrowing its power to bounce directly into a counterstrike, as in pak-da or pak-sau to fak sau.
4. Borrowed Response: You jerk down on an opponent's arm and they resist, lifting your arm up adding power to your strike to a high target as in jut-da punching the face.
5. Augmentation Principle: They punch, you deflect and pull, augmenting their force with yours, leading them into a throw, or pulling them into a wall, post or other hard object!
6. Spring Principle: They charge in, with their force bending and compressing your limbs, so when released your arms snap back like bent bamboo, adding their force to your own as in bong-sau to fak-sau. This springy energy is at the core of the WT lineage I trained. It is how we understand the old kuen kuit: Loi lau hoi sung, lat sau jik chung.
BTW these ideas are my own breakdown of what I learned from LT back in the early 80s and put into an article I wrote for Inside Kung-Fu at that time. Golly, remember when people read magazines?
