In a comment made on a previous question I asked, someone directed me to Moses 1:35 in the Pearl of Great Price. I read the context and saw Moses 1:32–33, which interested me as well. The text is as follows:
And by the word of my power, have I created them, which is mine Only Begotten Son, who is full of grace and truth.
And worlds without number have I created; and I also created them for mine own purpose; and by the Son I created them, which is mine Only Begotten.
In LDS teaching, Lucifer and Jesus are spiritual brothers, and, indeed, we are all brothers of both Jesus and Lucifer—both of whom are our elder brothers.
So, in what sense, then, is Jesus the Only Begotten Son of God according to LDS teaching, when in the pre-mortal life Elohim did have multiple sons (and daughters)?