Justifying Young vs. Spenser

So how do I justify Brigham Young's teaching with Spence W. Kimball's totally new and different concepts? This is what Brigham Young said:

"That slavery will continue, untill there is a people raised up upon the face of the earth who will contend for righteous principles, who will not only beleive in but operate, with every power and faculty given to them to help to esstablish the kingdom of God, to overcome the devil, and drive him from the earth, then will this curse be removed. This was the starting point of slavery. Again after adam, and Eve had pertook of the curse, we find they had two sons Cain and Able, but which was the oldest I cannot positively say; but this I know, Cain was given more to evil practices than Abel, but whether he was the oldest or not matters not to me. Adam was commanded to sacrifise, and offer up his offerings to God, that placed him into the garden of Eden. Through the faith and obedience of Able to his heavenly father, Cain became jealous of him, and he laid a plan to obtain all his flocks; for through his perfect obedience to father he obtained more blessings than Cain; consequently he took it into his heart to put able able of this mortal existance. after the deed was done, the Lord enquired to able, and made Caine own what he had done with him. Now says the grand father I will not distroy the seed of michal and his wife; and cain I will not kill you, nor suffer any one to kill you, but I will put a mark upon you. What is that mark? you will see it on the countenance of every African you ever did see upon the face of the earth, or ever will see. Now I tell you what I know; when the mark was put upon Cain, Abels children was in all probability young; the Lord told Cain that he should not receive the blessings of the preisthood nor his seed, until the last of the posterity of Able had received the preisthood, until the redemtion of the earth. If there never was a prophet, or apostle of Jesus Christ spoke it before, I tell you, this people that are commonly called negroes are the children of old Cain. I know they are, I know that they cannot bear rule in the preisthood, for the curse on them was to remain upon them, until the resedue of the posterity of Michal and his wife receive the blessings, the seed of Cain would have received had they not been cursed; and hold the keys of the preisthood, until the times of the restitution shall come, and the curse be wiped off from the earth, and from michals seed. Then Cain's seed will be had in rememberance, and the time come when that curse should be wiped off." (See: http://www.utlm.org/onlineresources/sermons_talks_interviews/brigham1852feb5_priesthoodandblacks.htm)"

There can be no doubt that this is what B. Y. taught! So how can we justify the two opposing ideas?

The way I justify it is this... Once any person is baptized into the Church of Jesus Christ of Latter-Day Saints, they are confirmed a member of the Church. You are then allowed to get a patriarchal blessing. The purpose of this blessing is to determine an 'adopted' lineage you will be assigned too. In many families two siblings might be adopted into a different lines... The Tribe of Ephraim is a common adopted line... and it is mine.

So once you are adopted into a "line of Adam" you are no longer in the blood-line of Satan. Through Jesus Christ this adoption is guaranteed if you forsake the blood-line of Satan and follow instead after Christ... We are all of the blood line of Satan at birth, and we must cast off our birth right with Satan, and follow the teachings and commandments of Christ.

It can't be more simple than that!