I'm not sure if this would help a bit but I hope so. My dad and his family emigrated to Taiwan from China in '49, escaping from the communism. His father was the last landlord, giving up everything. He didn't tell me much but he said that the land has been in the Yu family for several generations. Grandfather never had a job in his life until the family escaped to Taiwan from the southern part of China. I'm not sure if he has siblings that might be related to your family since they were also from Shanghai. Was there any of your family members part of the landowning business. Of course, the surname Yu is so numerous in China, making it a little difficult to trace back to the right ancestor. Also, my father once mentioned that we have over 200 relatives in Italy (!) that emigrated from China sometimes during or before the communist party's take over. Please let me know if you've found more information while I try to pull out more info from my dad, who's somewhat like your mom, reluctant to give out a lot of info. You can contact me at firstname.lastname@example.org
. Best luck!