To Be Number One - Ray Lui (1991) - Nam Sang Wai, Yuen Long

Ng falls for Tse Yuen-yin (Cecilia Yip) and ingratiates himself with her kids to get closer to her. In the story, she lives in a stilt house on a pond somewhere. I can't find the exact location unfortunately, but I am certain this was filmed in Nam Sang Wai. Sadly it's another place increasingly affected by redevelopment and many of the former ponds have already been filled in for redevelopment.