Poultney Church Record indicates Keziah Cowdery, Oliver Cowdery's stepmother, joined the congregation in May 1811.
Entry, May 26, 1811, Poultney Church Records, Book 3, Poultney, Vermont, Poultney Historical Society, in Wesley Preston Walters Manuscript Collection, Box 55, PCA Historical Center, St. Louis, Missouri
Chh voted to give Mrs. Keziah Cowdery a letter of recommendation
Also reproduced in Wesley P. Walters, The Use of the Old Testament in the Book of Mormon (Salt Lake City: Utah Lighthouse Ministry, 1990), 212