KPM did a bang up job of explaining the origins of wing chun and weng chun in an earlier thread...
Thanks for providing that link ....I'd forgotten about it. My old Wing Tsun sifu did research on the subject, wrote a book, and came to pretty much the same conclusion that Weng Chun and Wing Chun were always distinct arts that may have evolved from similar root arts, and so shared certain traits. Additionally, their practitioners had some contact and over the generations some borrowing or "cross fertilization" occurred, adding some more similarities. So, in KPM's words, "cousins" that share a name and some traits.