Elizabeth Collier (1747–1769)
Elizabeth Pole (1769–1781)
Elizabeth Darwin (1781–1832)

Née Collier. Illegitimate daughter of Charles Colyear, the second earl of Portmore. Married Edward Sacheverel Pole (d. 1780) in 1769. Became Erasmus Darwin’s second wife in 1781.

Sources

Darwin pedigree

England, select marriages, 1538–1973 (Ancestry.com, accessed 8 December 2015)