Shades of Gray (Grakowitz) Part 2; Helen Gray Death Certificate

Funny how a search for Abraham Kadetsky in Chicago on family search turns up new records on dead ends. Helen Gray's parents were Abraham and Shana Kadetsky. Abraham was Sussman Kadetsky's brother. Helen married Hersz Grabkovitz. They changed their name to Gray after coming to America from Sierpc, Poland. (see http://kadetskyfamilyhistory.blogspot.com/2011/06/shades-of-gray-grakowitz.html) They immigrated to Buffalo to Benjamin Kadetsky before moving west to Chicago. After the Holocaust they bought a page in the Sierpc Yizkor gathering. Hersz was Americanized to Harry. Harry and Helen had three children; Thressa, Rena and Marvin. I have been unable to trace the family beyond that. I just found Helen's death certificate. https://familysearch.org/pal:/MM9.1.1/QVRN-WFYY She died December 27, 1957 and was buried at the West Lawn Cemetery in Chicago on December 29, 1957. She last lived at 3114 Jerome Avenue. Her parents are listed as Abraham and Shaina Kadetsky. The informant was Laura Felles. Anyone know how to find Helen and Harry Gray's children.