The hard thing is, GM Yip learned at least 3 styles of Wing/Weng chun in his life. Tracking down all of those 3 histories makes it pretty tough.
Bully - are you doing cho ga wing chun?
No I try to do Ip Man lineage, sort of a bastard son of Kamon in a way. However when i was in China I was lucky enough to spend 5 weeks at Kung Fu school which taught Foshan WC, not sure exactly what flavour but I have looked for the forms on Youtube etc cannot find them.
So I know SLT and CK (not mastered, just know;-)) and bumble along doing these but I have the added bonus of Ershianshi (the Foshan form) which traditionally is taught before SLT so my master told me. They have 4 empty hand forms compared to our 3.
Alot more traditional in a Northern Kung Fu way if you know what I mean?? Some of the moves in the form would not be considered Wing Chun as we know it. I appreciated it for what it was and will continue to practice it. I see it as an addition to my training.