Search Half-brother Adopted by an American soldier this one was stationed in Germany

Hello, my name is Conny I search my brother he was born in Germany on May 12th, 1959 its name was Michael Bumer.It became adopted officiel in July 1960. He became a couple of days after his birth separated from his mother.The mother has never agreed to the adoption.She is extremely in despair.Our mother is 70 years old.She would like to get to know her son.She search for a long time.He has the name John Michael Whelikan now.Its adoptive parents are John Whelikan and Magareta Whelikan,She girl's name was Lyons.The adoptive parents have got married in Californien. In 1959 John Whelikan as a soldier was stationed in Germany.Exact in Idar-Oberstein or in Birkenfeld. Please help us.For the German authorities we don't get further.I don't find his last name in any American phone book.Where shall I search still? Somebody knows the name Whelikan?please, you help me. Many thanks first of all. Yours sincerely Conny