Don't assume that all the information on a death certificate is correct. On my great grandfather's (Ruperto's) death certificate, his son in law was the one who gave the information. Instead of listing his mother's name (Rosalia), he (son in law) listed my great grandfather's wife's name (Noberta) under the heading 'mother'. Always look to see who gave the information. In laws may not know the names of people who were there before, especially if they were already deceased.