Along the lines of authenticating your lineage...
Connection to ancestors... lineage... You can only go so far back when tracing the background of the training method you follow. The further you go back, the blurrier the picture becomes as not every relationship and every detail is documented.
Ving Tsun was developed by evolving over time, changing with each exponent. Early Ving Tsun versions were probably a far cry from what current practitioners train and teach today. Each exponent took what he learned from his teacher and passed on his interpretation of these teachings together with his personal experience to his students - sometimes for better, sometimes for worse. It suffices to look at your classmates to realize the wide range of skill and understanding that can be found even within the same lineage. Is it then worth to even spend time talking about lineage? Yeah, as it allows you to understand the historic factors that contributed to what you are learning. However, claiming this or that lineage as "authentic" (whatever that means in light of the evolution of Ving Tsun) is futile, as understanding and skill are not inherited.
Lineage claims are not so important in my book (even though they provide some background on what you may expect). I prefer evaluating Ving Tsun through the lens of 2 factors:
1.) The bottomline, does it work under realistic circumstances? Am I training attributes that are of value in a fight and that increase my chances for survival?
2.) Is the method adhering to the fighting strategies of Ving Tsun and the body mechanics tied to these? Is this done in a way that maximizes my potential?
Good fighting methods in general (boxing, MT, MMA, etc.) meet the first, good Ving Tsun meets both.