The reunification of the children of Israel, and the adopted children of Israel from among the Gentiles, will be accomplished by the unification of the records. The angel tells Nephi that not only will the Bible and the Book of Mormon be united in their declaration that the records of the prophets and apostles are true, but other records would as well.
We do not know what those other records are. Perhaps they are records waiting to be discovered. Perhaps, however, they are the numerous records from history that are helping to establish the history surrounding the events from the Bible and the Book of Mormon.
This ends a chapter in our current Book of Mormon, but did not end in the original. Nephi’s vision continues in the next chapter.