Daughter of Hiram and Sophia Lance Dayton. At the time of the 1850 Iowa census (taken in September) the family was living in Pottawattamie County. Isabelle is listed as Isabelle "Lance." Although her obituary indicates that the family traveled to the Valley in 1852, her father's name appears in the Salt Lake City Public Works record books on 2 January 1852, which was prior to that year's emigration season, so they must have traveled to Utah in 1851. Further research is needed to identify the company with which they traveled.
Isabelle married Harmon William Cummings. Her death certificate confirms her birth and death dates and shows her name as "Isabella Florinda Cummings."
At the time of the 1856 Utah Territorial census the Dayton family was living in "St. One City," Utah.