sharon martin

i am trying to follow through on who my grandfather on my dads side is. My dad Peter James Arthur dob 12 July 1927 at St Marys home for unwed mothers in Otahuhu Auckland.His mother was Margaret Joyce Arthur and she was from Thames on the Coromandel Pennisula. Dad did have younger sibilngs but they no nothing. For several years I was told to leave it alone as it is not important. It is very real and important to me, my children and my grand babies. how do we when no details are listed find our grandfather and this side of our family. Thanking you for any help, Sharon Arthur