What you quoting are discoures they are not scripture nor doctrine and never was consider as such!
Learn to spell and lose the exclamation point.
It is an approved copy of a speech by Mormon President Brigham Young in the new tabernacle at Salt Lake City, Utah, on October 30, 1870. It was taken down in shorthand by one George Watt, his clerk, and published. I would not presume to argue with such an august fellow in the LDS church about what their beliefs are.
From a non-Mormon POV, they both were created by God the Father and pre-existed for some time, Jesus certainly/probably from the beginning. Now I read in my bible that Lucifer had some sort of special status before he rebelled and took 1/3 of the angels with him. So what is wrong with thinking of them of at least spiritual brothers? Cain and Abel were brothers. One ended up murdered by the other. Jesus, I guess I'm supposed to believe he was the only begotten son, I don't really know what that means theologically (please don't try to explain it). I believe Jesus had a creator role. He was foreordained to be the savior. Lucifer was the Morning Star whatever that is.
I'm going way out on a limb here :-) and state emphatically that I do not believe any Mormon thinks Jesus and Lucifer were on good terms after the fall. They became enemies after that. Before that? I doubt it if they were both doing the will of the Father.
Now this is just my personal opinion, but I believe that Lucifer can muck up creation but I can't cite a bible passage. I just believe he can manipulate life to a certain extent, who, what, and how, don't ask, I don't know. He just can't create it.
So what is the big deal about it really? Probably that the remark was intended to be derogatory and inflammatory. For that reason he should apologize. If the apology was heartfelt and sincere. How do we know? We don't. At least it was a reaching of sorts across the great divide.
You might want to find another "English as a Second Language" teacher. Your current instructor is stealing your tuition.
Well... the LDS church still quotes from them, and the Deseret Book Store had this to say:
"If anyone tells you that the sermons found therein are not recognized by the Church, they know not what they are talking about."{click the image for more info...}