According to The Annals of Brookfield, Fairfield County, Connecticut, by Emily C. Hawley, Charles Oliver Barnum was also known as Oliver Hamlin Barnum. Oliver Canfield Hamlin was a brother of Charles' mother, Sally Arline Hamlin. Both were children of Russell Hamlin and Sally Benedict. Oliver C. Hamlin died at the age of 30, in 1845, and it appears that Sally renamed her son after her brother. Oliver C. Hamlin's widow Mary remarried and they all (she, plus her new husband and her two children by Oliver) relocated to Michigan.