Genesis 50:23

The third generation. — These would be Joseph’s great-grandchildren. Thus Eran, son of Shuthelah, son of Ephraim, was to be born in Joseph’s lifetime (Numbers 26:35).

Were brought up... — Heb., were born upon Joseph’s knees, that is, were adopted by him. (See Note on Genesis 30:3.) They would not form tribes, as this prerogative was reserved for the sons of Jacob (Genesis 48:5), but they would count as Joseph’s sons (Genesis 48:6), and form “families.”