Orson Pratt explains authorization is needed to enter plural marriage.
Orson Pratt, "Celestial Marriage," The Seer 1, no. 2 (February 1853): 30–31
Now in the early rise of this church, the Lord gave no command unto any of His servants authorizing them to take more than one wife, but on the contrary, said unto them that they should give heed to that which was written in the book of Mormon; therefore, they were under the strictest obligations to confine themselves to one wife, until a commandment came to the contrary, which the Lord did not see proper to give unto any of them, until about thirteen years after the first organization of the church. The church, therefore, are still restricted, by the severest penalties, to one wife, according to the Book of Mormon, unless in individual cases where the Lord shall, by revelation, direct otherwise.
No man in Utah, who already has a wife, and who may desire to obtain another, has any right to make any propositions of marriage to a lady, until he has consulted the President over the whole church, and through him, obtains a revelation from God, as to whether it would be pleasing in His sight. If he is forbidden by revelation, that ends the matter: if, by revelation, the privelege is granted, he still has no right to consult the feelings of the young lady, until he has obtained the approbation of her her parents, provided they are living in Utah; if their consent cannot be obtained, this also ends the matter. But if the parents or guardians freely give their consent, then he may make propositions of marriage to the young lady; if she refuse these propositions, this also ends the matter; but if she accept, a day is generally set apart by the parties for the marriage ceremony to be celebrated.