Looking for my great godfather Robert Gerardin?

Question:

Looking for my great godfather Robert Gerardin?

Please suggest or advice on how I can find information about this French person and his family.
He adopted my grand dad when he was orphaned as a little kid. He raised and provided for my parents and other Vietnamese people in Vietnam. Yes, he was French person living in Vietnam before the Vietnam war.
When he fled Vietnam, we lost all contact with him. All his memories and details were burnt in fear of the V.C. We don't have any official records that he adopted my grand dad.
The only details I have about him is:
Born Robert Gerardin, had 2 daughters-youngest one is named Colette. Colette would be 80 something now.
Robert divorced his wife and left his daughters in France before he moved to Vietnam in his late Twenties. Returned home to France in 1977(around this time). He was around 83 years when he died in Nice, France around the year 1981-1984.
I'm want to visit his grave and pay my respect. Also, I would like to get in contact with his remaining family members.

Thank you

Best Answer - Chosen by Asker: French genealogy records aren't easily accessible from the US. There is a fabulous site called GeneaNet, which is the main contact point for all French genealogists so you might be able to make contact with a kindred spirit who's willing to do some searching for you. Many of the researchers do speak English, you just have to snoop around to find them.