William Price POW Marine has daughter

I am helping my daughter do research with little to no information. She knows her paternal grandfather was a POW for 3.5 yrs and I believe he was in Shanghai..He had a daughter born while he was in the Marines. She would be about 56-60 by now...His name was William M. Price. As I stated he was a marine..Also he was from Mississippi. At one time their was a picture he carried of his daughter born there..I doubt very seriously we would find her but it would sure be wonderful. This is so little of information to go on but I thought I would at least attempt this. My fatherinlaw has been dead since 1976 and his son (my exhusband) is also deceased...My daughter would like very much to hear from the lady that could be her real Aunt...Her father has one living brother that is 50 but he doesnt know any of the family history..SO please write if you know anything..THANKS..You never know she could be searching as well...GOD BLESS...