The sons of Ephraim - The genealogy is difficult. It is perhaps best to consider Ezer and Elead 1 Chronicles 7:21 as not sons of Zabad and brothers of the second Shuthelah, but natural sons of Ephraim. The passage would then run thusly:
“And the sons of Ephraim, Shuthelah (and Bered was his son, and Tahath his son and Eladah his son, and Tahath his son, and Zabad his son, and Shuthelah his son) and Ezer and Elead, whom the men of Gath slew” (i. e. the settled inhabitants, as contrasted with the nomadic Hebrews, Amalekites, etc.).