Yue Jia Quan is basically a southern Hakka style, it has an important form called San Men Quan. 3 gates fist.

I've been looking at all my resources that have this set, and I am having a hunching from what I see, that THIS style is what Southern Tai Zu is based on!
Yue Jia Quan's 3 Gates Fist is not much different from 3 Battles Fist.

I bet the Hakka grand ancestor was referring all along to their actual real southern song Grand Ancestor who is a hakka too: Yue Fei ! He's the grand ancestor in honor, not Zhao Kuan Yin, and it really fits prefectly with the correct time period when the hakka last wave came down into the south.