My father told me little about his ong ngoai (maternal grandfather). All he knows is that he was a merchant or sorts who traveled around Vietnam at the later parts of the 1800's (north and central of modern Vietnam). He had 8 wives living in the 8 different parts of Vietnam he visited. Each of the 8 wives had 1 child and my paternal grandmother was the 8th child from the 8th wife.
My dad spoke of an uncle that lived in Saigon (Ho Chi Minh City) back in the 1960's. This uncle was the 1st child of the 1st wife.
If any of this sounds familiar to you, please contact me. I would love to know more about this mysterious of the family.