Looking for Tran Thi Luyen in the US

If she's alive, she is around 68 years old.
She is Vietnamese, and moved to the US since 1977.

She is older sister of Tran Khanh Dung. And Dung is close friend of Jimmy Mcdowell – who died in 1972 due to infection.

Now the youngest brother of Jimmy – Peter – went to Vietnam to find info about the life of his dead brother. He wants to find info about his brother's friends, specially Luyen and Dung.

We have tried all ways:

+ Visiting neiborhood to ask old people.
Old address was “75/5 Ap Tan Sa Chau, Gia Dinh, Saigon”
+ Contact local government/police.
+ Write to few pages in Vietnamese
+ Contact the TV program “Như chưa hề có cuộc chia ly” (As the separation never happened)

Any information will be very helpful.

Pictures can be seen at https://jimmyinsaigon.com/