Find Ancestors

I can' believe that no one knows any of these people please help! I am married to Ken Nevins (d.o.b 30/11/62) who parents are John Nevins, last residing in Hilborough Hall, Norfolk and Marie Nevins (now I think surname is Mcgiure) living in Ireland. Ken and his sister Jackie were sent on a plane to Ireland in 1969 saying they were going to visit a aunt and uncle in Ireland. It turns out that Ken & Jackie;s father, John Nevins, had put an ad in the Irish newspapers for someone to look after 2 children over the school holidays and paid them well to do so. It turns out Ken's Dad never went back for them and Ken & Jackie were left in ireland with what turned out to be a nasty family and they had a miserable existence. Ken came over to England in 1986. His father John Nevins , last known address Hilborough Hall, Norfolk had apparently remarried to a lady named Gillian and he has 4 half sisters, one called Portia. His mother Marie, now Mcgiure? resides in Ireland and has her own family. i am trying to trace any half sisters/brothers who may not know of Kens existence and Kens mum and Dad who I would love to meet so their grandchildren may know them. Ken has a youinger brother John who was adopted who I would also like to trace. Any help would be appreciated. Sharron Nevins