The United Order appears to be divine, going by a breakdown of it. Find a breakdown here. (MormonThink).
The original version of The Book of Commandments in 1830 says that an angel was the way Joseph Smith, the translator of The Book of Mormon, learned about the book.
While the general reference preceded a mention of a particular name, it does assert an angel in 1827.
(more at MormonThink)