This is the biggest hoax in the world! I just read the comparison between the Book of Commandments and the D&C add-ons!!!!! JS shall pretend to no other gift other than that of translation!!!! Book of Commandments 4:2 vs D&C 5:4. AND the added Priesthood revelation in D&C 27:8 that was not in the 1833 Book of Commandments (XXVIII:6). WOW!!!!!!!! This never ends does it!
What really cracks me up is how the heading to Sec. 132 says "Although the revelation was recorded in 1843, it is evident from the historical records that the doctrines and principles involved in this revelation (polygamy) had been known by the Prophet since 1831."
What does that mean? "Since Emma found out that Joseph had been screwing other women for 12 years, he finally had to come up with a revelation to cover his ass."
Yes, D&C is the "sealed, or unopened, book" of Moism. If any member will actually take the time to read the whole thing, and understand the historical contexts of each section, it is highly unlikely that they will maintain any testimony. It's pretty transparently false in every way.
Reading John Tvedtness's "Organize my Kingdom" was a big eye-opener for me. The story is your basic restoration crap, but his footnotes contain all these comments on different versions, merging and date-fiddling.