Found her on the 1940 Bronx, New York census (dist 3-122A img 13) as
Katherine Arms age 11.
Nelligan, Katherine A., 87, a longtime resident of Bedford Hills, died Saturday in Westchester. Katherine was born at home in the Bronx on November 29, 1927 to the late Philip and Frieda Finger Arms.
She graduated valedictorian and president of her class at Walton High School. Katherine was trained as a legal secretary and worked in the practice of Albert V. Marchigiani. Upon his election as Supervisor of the Town of Bedford, she moved to serve as his administrative assistant for the township. She continued to serve as administrative assistant to seven Town of Bedford Supervisors in a career spanning over 27 years until her retirement.
She was a founding member and trustee of the Bedford Hills Historical Society, and a docent at the museum. She was also an active member of the Bedford Hills Women’s Club. She enjoyed spending time with her family and her active lifestyle included travel and twice-weekly aerobics classes until shortly before her death.
Katherine is survived by her sister, Frieda Thompson and she is also survived by her five children: Kathy, Kim, Karen (John), William (Ann) and Kelly (Stuart), and her grandchildren: Joe (Dana), Matthew (Laura), Billy (Krystal), Christopher (Julissa), Jeffrey (Kseniya), Hannah, Katherine, William IV, Jack, Ben, and John-Michael. She is a recent great-grandmother to Grace, Maya and Jennie. She is predeceased by her two brothers, both named Philip and her son-in law, Frank.