Helen Mar Kimball Whitney gives seconhand account of her father being introduced to plural marriage in July 1841.
Helen Mar Kimball, "Scenes in Nauvoo," Woman's Exponent 10, no. 6 (August 15, 1881): 42
On the 1st day of July my father with President Young and Brother John Taylor arrived home from their mission; the families of the latter who were left in Montrose sick, were then living in Nauvoo on the Flat enjoying a more comfortable degree of health. . . . My mother felt the presence of others at such a time almost an intrusion but Brother Joseph seemed unwilling to part with my father; and from that time kept the Twelve in Council early and late, and she sometimes felt nearly jealous of him but never dreamed that he was during those times revealing to them the principles of Celestial Marriage and that her trials and sacrifices which she had flattered herself were nearly over, had scarcely begun, and they little realized the meaning of his words when he said "he was rolling off the kingdom from his own shoulders on to the shoulders of the Twelve."