Questionable Fact: Family Name

The Original Story:
Fu Ping was told that her Shanghai parents are not her biological parents in the most brutal fashion: by a group of Red Guards who had come to take her away. She was 8 years old. As she was riding on the train to Nanjing alone, she reflected on Pages 21-22 of Bend, Not Break:

But the truth of the matter was, there had been hints before that I'd been adopted. I remembered a time when my older sister had complained that my brothers were giving me a longer sedan chair ride in their arms than they were giving their "real" sister. I had run inside the house crying. Mama had assured me that she was my real mother. 

"Ping-Ping," she had said, stroking my hair, "you're so special that you needed two mothers to give birth to you."

She also remembered that she

found it strange that Shanghai Mama had always asked me to call her sister "Nanjing Mother," as opposed to "Auntie." Still it had never occurred to me that Nanjing Mother might be my real mother.

The Debunking:
When Fu Ping was still enjoying sedan chair rides from her brothers, she must be at a very earlier age. Thus it is reasonable that she wasn't immediately alarmed or confused by the statement that she "needed two mothers to give birth to."

However, one thing she did not mention in her book is the last name of her Shanghai father. Fu Ping's Shanghai mother is the sister of her biological mother. So they share the same last name which is different from that of Fu Ping and her biological father. (In China, women do not change their last name after marriage.) Presumably, all other children in the Shanghai family have the same family name as their father, i.e., Fu Ping's Shanghai Papa.

Unless her Shanghai Papa happens to also have the last name "Fu," Fu Ping should find herself with a last name that is different from her siblings and her "parents." This should have come to the attention of a girl who was reaching the age of 8. Yet, no mention of this in the book.

What would be the chance that her Shanghai Papa would have the same last name of her Nanjing Papa? "Fu" is not a very common family name in China.