Apparently, a birth certificate for Grace was never filed with the state of New Jersey around the time she was born or it was misfiled. I have searched for it in the New Jersey Archives in Trenton without success while finding birth certificates for each of her siblings there. A delayed certificate was issued in 1943 by the city of Rahway. 
Grace's mother, Sophie (Bettinger) (Hamill) Hamill, kept a record of her children's births in the back of a small book, "Our Marriage Vow," which she received when she married Richard Hamill, her second husband, and Grace's father. She recorded Grace's birth there. 
 Babish family traditions regarding Grace Hamill receiving dolls as a gift from her half brother Albert, Daniel Babish compiler (email message, 17 February 2014), as reported by Victoria Babish, Grace's daughter, February 2014.
 Birth Certificates, City of Rahway (Rahway, Union County, New Jersey, Registrar of Vital Statistics), Grace Evelyn Hamill; Rahway, Union County, New Jersey; 14 February 1914 (delayed) issued 17 May 1943; Original copy in Daniel Babish household, 2014.
 Thomas Whittaker, Our Marriage Vow: The Service and Minister's Certificate (New York: 2 and 3 Bible House, 1877); "Born", entry of births by Sophie (Bettinger) (Hamill) Hamill; Original copy in Daniel Babish household, 2014.