Find Ancestors

I am trying to find information on the following: John Burke and Mary Fitzgerald. Both were born in Doneraile co. Cork - John a labourer was born 17th October 1909 and Mary 2nd March 1912. They both moved to Jersey Channel Islands probably in the early 1930's were married there and had six surviving children - Roseann, my mother, Eileen, Margaret, Kathleen, Teresa and Thomas(Tommy). They died in the mid 1970's. I am trying to search for their parents but know virtually nothing about John Burke except that he possibly had 1 or 2 sisters and maybe a brother. Mary had a sister Nell - who also moved to Jersey - Josie, Madge, John and Bridie. There may be others I dont know about. I know that Nell married Alfie de st. Croix from Jersey and I believe Josie married Peter?. I have also been told that Bridie has two children called Sean and Peter and that Madge may have had a son called Patrick. I dont know the names of Mary Fitzgeralds parents were except that her mother may have been called Bridget . Any information would be most appreciated as I am at a brick wall. Please help!!!!

Thanks and good luck