Looking for my daughter

I was in Vietnam for a little over 4 years. During my second time in country I met and fell in love with a girl from Tay Ninh. We dated and were making plans to be married so she could return to the states with me. We had a little girl together who we named Thanh van Hungh. Her mother, Tran, was half French and half Viet but was killed by the VC when they were attacking our camp in Trung Sup, just outside of Tay Ninh. Thanh was left with Tran's parents who were relocated or moved to the Delta. Exactly where in the Delta, I just do not know. I was never able to find that information. When this happened I knew nothing about the move and lost my daughter. That was in 1965 through 1966. I have tried other sources including the VNN and Datviet but to no avail. I am now 60 years old and would love to have my daughter back in my life. Anything you can offer me by way of guidance will be greatly appreciated.