I am trying to trace the ancestry of my grandfather, HERMANN FRIEDRICH WILHELM KNAAK, born 31 May 1881 in Lubeck, Schleswig Holstein, Germany, died 6 August 1916 in Verdun, France during WWI. He was married to my grandmother, FRIEDERICKE MARIE SOPHIA DOROTHEA (LUCKMANN) KNAAK. His siblings may have possibly been named RUDOLF KNAAK, whose wife may have had the given name of META, ERWIN KNAAK, and IDA KNAAK. My grandfather's parents (my great grandparents) were FRIEDRICH KNAAK and either WILHELMINE SCHULTZ or ______ LUCHTERHAND. It is my great grandparents that I would like to know more about, and also find out which of these two women was my great grandmother. I would also like to know more about my grandfather's siblings or half siblings, RUDOLF, ERWIN and IDA KNAAK.