The old news: Some “orthodox” polygamy continued after the 1890 Manifesto. James G. Duffin, president of the Southwestern/Central States Mission from 1900 to 1906, and Amelia B. Carling, one of the early full-time, full-length single-sister missionaries (1901–1902), married polygamously in 1902. 
The new news: Duffin and Carling courted while she was a missionary under his supervision; their marriage took place before her release or immediately thereafter. (I assume Quinn knew it, but I haven’t found a publication pointing out this detail.) 
First, a punctuation change: Mission president and sister missionary in the same mission marry polygamously! Without excommunication! 
I’ve been poking into President Duffin’s diary for the past five-plus years but just figured out he was a polygamist two weeks ago. Having made the connection, I suddenly changed how I read. First, I became hyper suspicious. Now when I read things like, “To-day Sister Richards and self returned to Kansas City,” my spidey sense tingles.  Once you start using numbers other than one or zero in marital relations, every woman you spend time alone with sounds intriguing to this historian. See also: Duffin’s trips to Canada with Apostle John Taylor—was he looking into a third match? And the “farewell reception” for Sister Carling at the end of her mission—was it a crypto wedding reception? 
Another casualty I observed was the supposition of laziness. Normally people leave piles of stuff out of their diaries or write unclearly, so one laments and then moves on without second thoughts. Discovering Duffin’s polygamy turned me into a conspiracy theorist finding code in every syntactical wiggle. For example, in Nov 1903 Duffin “spent a very pleasant week at Dublan visiting friends and relatives” (my italics). Since Duffin had a wife and child in the colonies and was “met at the station by A.,” I read him as indicating his plural family and supporters. It holds for 1904 and 1905 trips to Colonia Juarez but seems a stretch for a 1905 Toquerville trip where he mentions “our relatives and friends” but also identifies his mother and a sister.  Along the same lines, when Duffin delivers letters “from a friend of mine” to “Sister Cowley and Sister H.,” I wonder whether he is intentionally hiding identities. 
Going even further from the text, when Duffin bears testimony “that every principle revealed through Joseph Smith, the prophet, is of God,” I imagine that “every” is underlined—even though Duffin did not underline it. Similarly, when he writes, “[i]t is my desire to serve the Lord all the days of my life, to be true to all of my family and to the servants of the Lord and His holy laws. …Opposition will come from both members and non-members of the church,” I imagine that “all of my family” and “opposition” indicate polygamy, but I can’t prove it without first assuming that he’s a polygamist staking a claim to Smith’s prophetic legacy. 
A final example: “Had a nice private conversation with Prest. Smith…. Many things were said that I shall not write.”  I assume it-that-shall-not-be-named, in 1905, involves polygamous goings on. Part of the conversation involved Duffin delivering “a message sent by Apostles Cowley and Teasdale, giving him their confidence and loyal support,” so we know polygamy was… well, actually, just because Elder Cowley was involved doesn’t mean it was about polygamy. The church was already an extensive and complicated organization. For all I can prove from the words on the page, they were planning a surprise birthday party.
Thus, post-Manifesto polygamy makes for a pesky epistemological pickle: once you’ve established someone is deliberately hiding information, if you don’t always assume they’re lying, you’re likely to miss the story; on the other hand, if you always read intentional deception, you’re likely to turn the source into a question-begging Rorschach test.
If you get bored with epistemological koans, there’s always post-facto irony, like when Duffin recorded, two to three months post-marriage, an apostle’s counsel to the missionaries to “avoid wine and women as you would avoid the gates of hell.” President Joseph F. Smith taught, during a 1903 visit, that “If any man is untrue to his wife he cannot keep the spirit of his calling. Elders should not seek for a wife here in the mission field. It is his duty to preach the gospel to the people. Turning to the Elders and saints he said: ‘We have confidence in Brother Duffin.’”  Another instance when I found myself saying, “Holy Compartmentalized Psychology, Batman!” comes from the 1904 May 18 entry where Duffin records that on the train en route to visit his second wife and child in the Colonies he “met Congressman Smith of the western district of Texas. He informed me that he was present when the testimony of Prest. Smith was given before the Senate Committee in the Reed Smoot Case. His district is about 600 by 700 miles in extent.” It’s not a dead pan; it’s a pan that lives in a cosmos where it is righteous and normal to have more than one wife and to hide it from the government. At least to my diary-reading eyes.
So, I haven’t, um, figured out how to write self-contained, reasonably-lengthed blog posts, so I’m doing another multi-part post. This time, however, I’m going to spread it out over weeks instead of posting every day. Future posts will evaluate earlier treatments of Duffin-Carling, the evidence for their polygamy, and their marriage’s impact on sister missionary-hood—all from the perspective of critical reading methodology.
 Quinn, D. Michael (1985), “LDS Church Authority and New Plural Marriages, 1890–1904,” Dialogue 18(1): 93 (9–105). Quinn put Carling and Duffin together in a 1991 talk: “let me…give you a list of the prominent women who entered into plural marriages after the Manifesto. …Amelia B. Carlin, one of the earliest lady missionaries in 1901 to 1902, became a plural wife in 1902 of mission president James G. Duffin.” D. Michael Quinn, Bluffdale, Utah, 1991 Aug 11, unofficial transcript posted, but not prepared, by Perry L. Porter, accessed 2008 Oct 30. Neither Van Wagoner (Mormon Polygamy: A History) nor Hardy (Solemn Covenant: The Mormon Polygamous Passage) mention Duffin or Carling in their indices; Hardy includes Duffin and Carling in his tabulation of known post-Manifesto polygamous marriages (Appendix 2). I haven’t checked Cannon (1978, 1983) or the Salt Lake Tribune (1902-1915). Duffin was first cousin once removed to Joseph F. Smith; Carling was a connection of the gun-maker Browning family.
 I am focusing on Duffin’s experience and perspective, hopefully without implying that Carling was a passive participant.
 In a later post I’ll discuss possible gender implications of the Duffin/Carling marriage and, in particular, how it might affect Lyon and McFarland’s article, “Not Invited but Welcome: The History and Impact of Church Policy on Sister Missionaries” (Dialogue 36, no. 3 (2003): 71-101), which cites Duffin. (Spoiler: it adds a wrinkle, but does not appreciably alter their conclusion.)
 Duffin Diary, 1903 Nov 30. The diary is available in transcript and color image at the “Mormon Missionary Diaries” website hosted by the Harold B. Lee Library at BYU.
 Canada: 1905 May 13 and others; Farewell reception: 1902 Sep 23.
 Relatives in Mexican colonies: 1903 Nov 22, 23, 1904 May 22, 1905 May 13; in Toquerville: 1905 Mar 19.
 1904 Apr 02. See also the 1904 Apr 04 entry where Duffin “Had a talk today with Bro. Owen A. Woodruff about some matters that affect both his and my own welfare.” Elsewhere in this paper I conjecture that in 1902 Aug Duffin uses “friend” to refer to Apostle Cowley.
 Every principle: 1904 Mar 30; opposition: 1905 Dec 25.
 1905 Mar 14.
 1902 Nov 17; 1903 May 03.