Expected interactions based on geography: (1) Rigdon, Spalding, Pratt and (2) Cowdery and Smith.
Authorship attributions and allegations:
1. Joseph Smith — Joseph Smith, Jr. was published as the “author” of the 1830 Book of Mormon.
2. Joseph Smith, Jr. and Oliver Cowdery — The Cleveland Herald (Nov. 25, 1830) stated: “Mr. Cowdry and Mr. Smith the reputed author, have taken the old Bible to keep up a train of circumstances, and by altering names and language have produced the string of Jargon called the “Book of Mormon”… http://www.sidneyrigdon.com/dbroadhu/OH/miscohio.htm#112530. Painesville Telegraph Nov. 16, 1830: “About two weeks since some persons came along here with the book, one of whom pretends to have seen Angels, and assisted in translating the plates… The name of the person here, who pretends to have a divine mission, and to have seen and conversed with Angels, is Cowdray…” “Mr. Cowdry and Mr. Smith the reputed author, have taken the old Bible to keep up a train of circumstances, and by altering names and language have produced the string of Jargon called the “Book of Mormon”…Cleveland Herald Nov. 25, 1830. http://www.sidneyrigdon.com/dbroadhu/OH/miscohio.htm#112530 In 1849, Orsamus Turner alleged that Oliver Cowdery was the main contributor: “the book itself is without doubt a production of the Smith family, aided by Oliver Cowdery, who was school teacher on Stafford street, an intimate of the Smith family, and identified with the whole matter”. Orsamus Turner was a neighbor of the Smith’s in Palmyra, and a childhood friend of Joseph Smith’s.
3. Joseph Smith, Jr. — On February 7, 1831, Alexander Campbell named Smith as likely author in the Millenial Harbinger : “Joseph Smith, Junior, Author and Proprieter… Smith, its real author, as ignorant and impudent a knave as ever wrote a book, betrays the cloven foot in basing his whole book upon a false fact…”. By January 1835, after reading Mormonism Unvailed, Campbell had changed his mind in favor of the Spalding-Rigdon Theory as first proposed by Eber Howe in Mormonism Unvailed (1834).
4. Sidney Rigdon — The Cleveland Advertiser named Rigdon as likely author on February 15, 1831: “Rigdon was formerly a disciple of Campbell’s and who it is said was sent out to make proselytes, but is probable he thought he should find it more advantageous to operate on his own capital, and therefore wrote, as it is believed the Book of Mormon, and commenced his pilgrimage in the town of Kirtland, which was represented as one of the extreme points of the Holy Land” Anon. (1831). Mormonism – or Grand Pugilistic Debate. Cleveland Advertiser, February 15, 1831.
5. Solomon Spalding — In Feb 14 or 15, 1832, Mormon missionaries Orson Hyde and Samuel Smith read passages from the Book of Mormon at a schoolhouse in Conneaut (New Salem), Ohio. Nehemiah King, who was present at these readings, claimed that Hyde ‘had preached from the writings of Solomon Spalding’ (Wright, 1833). In December 1833, the Wayne Sentinel of Palmyra, New York, credited authorship of the Book of Mormon to “a respectable clergyman now dead”. Subsequent reports identified the clergyman as the late Reverend Solomon Spalding.
6. Solomon Spalding and Sidney Rigdon — Eber Howe published the Spalding allegations in Mormonism Unveiled (1834), including 8 statements from Conneaut witnesses collected in late 1833 by Ex-Mormon, D. P. Hurlbut. In 1834, Howe linked Rigdon to the Patterson bookshop in Pittsburgh, where Spalding allegedly submitted his manuscript for publication in 1813, and where Rigdon contributed book bindings through his work as a tanner. By the end of the 19th century, at least 16 witnesses had made claims that a Spalding manuscript served as the narrative basis for the Book of Mormon, with many identical names and frequent usage of the phrase “came to pass”. In the Millenial Harbinger No. I, Vol. VI (January 1835), Campbell said: “No man, not already duped, who has the half of five grains of common sense, can read this narrative of Mormonism without being converted to the belief that Joseph Smith and his colleagues in the plot are a band of the most unprincipled deceivers that ever disgraced any age or nation, and that his followers are a set of superlative fanatics”. In the Millenial Harbinger No. III (June 1839), Campbell said: “Since reading “Mormonism Unveiled” we had but little doubt that Sidney Rigdon is the leading conjuror in this diabolical affair; and that the widow of Solomon Spaulding, if found, could give some authentic and satisfactory information on the subject of the Book of Mormon — so far at least as the romance of Mr. Spaulding, the real basis of the fraud, was concerned. It would seem that she has been found in the wife of a second husband, Mrs. Davison, and that the whole affair is now at length fairly divulged. Much pains ought to be taken to send this document through the length and breadth of the land — as the emissaries of Smith, Rigdon, and Co., like the father of lies, are ever on the alert to beguile unstable souls, and continually lying in wait to deceive. The gullibility of the present generation has not, in the memory of history, been often equaled — never surpassed. A people ignorant of one Bible are always an easy prey to the ministers of delusion and error”. http://www.sidneyrigdon.com/dbroadhu/OH/evan1832.htm
7. Parley P. Pratt — In 1842, the Rev. Samuel Williams named Pratt as Rigdon’s probable accomplice and connection to Smith (Mormonism Exposed, Pittsburgh, 1842 pp. 5-6). Samuel Williams (1802-1887) was Pastor of the First Baptist Church of Pittsburgh from 1827 to 1859. Rigdon was its pastor from 1822-23.