What is the meaning of "v'Alav"?
Rashi (citing Targum Onkelos): It means 'next to'. 1
Why it does not say "veha'Chonim Alav", like it says in Pesukim 5, 12 and 27?
Moshav Zekenim citing R. Yehudah ha'Chasid: It is because Efrayim and Menasheh resemble one Shevet.
Moshav Zekenim: Every Shevet had a river coming out of Miryam's Be'er, [that supplied it with water]. There was only one river for Efrayim and Menasheh.