When Jacob talks about polygamy in the Book of Mormon as a means to raise up seed to the Lord (Jacob 2:30), similar to other posters, I don’t interpret that to mean numbers at all.
I think of when Christ was trying to teach the people of his day when he said that God could raise up seed to Abraham of “these stones” — I read that to mean that he was trying to drive home the point that lineal numbers in and of themselves meant squat.
On the other hand, when Christ and various prophets in the scriptures venture to teach us about becoming God’s seed or a son or daughter of Christ, it seems that they are repeatedly pointing us to a significant qualitative change in the individual — a sacrificial abandonment of one’s own will to wholly carry out God’s will forevermore and covenants are always a part of that process.
Personally, I have come to see the Nauvoo women in particular who entered into the practice, not as being those who raised up seed to the Lord but AS BEING THOSE WHO BECAME HIS SEED in the initial spiritual crucibles many of them went through in entering into PM and in ongoing acts of wholly abandoning their cultural and personal preferences/norms to devote themselves to continuing therein as a matter of following God’s will no matter what it required.
In other words, imho, the righteous Nauvoo men and women who entered into PM were themselves the seed that were raised up unto the Lord and with that covenant, God now not only had his gospel again on the earth, He truly had a people.
Comment #77 by Laura on Why BIV Totally Would Have Slept with JS - StevenP (By Common Consent)