Question for Grandpa

My neighbor and I have been trying to figure out more about the lost tribes. In mormon doctrine it says that Ephraim was with the other ten tribes that were driven into Assyria then they were lead to the lands of the north. In Doctrine Covenants 133 26-35 is says that the lost tribes will come to the children of Ephraim to be crowned with glory. Did Ephraim some how come to the americas? How are his children not lost with the rest? Most of us in our Patriarchal blessings we from the tribe of Ephraim...are we lost?