mook jong man
Senior Master
This just highlights that even in Wing Chun, there will be differences
On your double bong sau though, if you are on an angle addressing your attacker's centerline, aren't your hands at different distances in relationship between his body and yours? While perhaps this is a weakened structure, it still seems to be within the 2 line theory.I don't want to talk too much more because it's supposed to be a karate thread lol.
But you know the double Lan Sau from Chum Kiu , if you change both your arms from horizontal to a 45 degree angle then you have the position for the Double Bong Sau.
The arms will be slanted with the middle of the forearms on the centerline , it's a very strong structure.
From that position the top hand will lop sau the attackers wrist and drag him into a Fak Sau to the throat.