The LDS historical department just published an 1886 polygamy revelation

The key issue here is that Taylor was head of the LDS and is said to have similar authority in the LDS church to the Pope among Catholics. So you have within a few years one LDS head endorsing polygamy, followed by another rejecting it to more or less save the Utah Mormon project.

And of course, on the light side, you have Mark Twain's brilliant refutation of polygamist claims by pointing out that the Bible does indeed condemn polygamy in the first half of Matthew 6:24.

Scratching my noggin and remembering Walter Martin's "Kingdom of the Cults", I'm reminded of how Martin noted that there were, even in the 1990s, something like 25,000 places where the most recent version of the Book of Mormon differed from the 1840s original. It's mostly where grammar and such is corrected, but of course, if you're talking about a book supposedly translated under the guidance of the Almighty, that puts a serious crimp on the authority of your text.