We seriously need to study the word "seed." Abraham here connects it with being ordained a priest. "Raising up seed" connects a strange and hard to understand series of texts: Tamar and Judah, the widow of seven brothers, and the Nephites' whoredoms in Jacob's day. The priesthood has to do with seed.
Lehi's party brought with them "seeds of every kind." So did the Jaredites. Might this be a reference to carrying a genealogical right to the priesthood in their midst?