1)
What is "l'Acharisech"?
1.
Radak: It is the end of your children.
2.
Malbim: It is at the end of days, at the deadline [for Mashi'ach]. Bnei Yosef themselves will not return, but their children - the last generation - will return to their border. They are not "b'Eretz Oyev"; they live by themselves in a land far from their border.