Genesis 43:29

‘Benjamin was his brother.’ All the brothers were sons of Joseph’s father. But only Benjamin was a son of Joseph’s mother.

Joseph called Benjamin ‘my son’. But that was a common greeting by an important person to someone who was young. Joseph was not saying that Benjamin was a relative.

v32 The servants brought food to Joseph apart from the other men. The brothers also were apart. And the Egyptians who ate with Joseph were apart. The Egyptians did not eat with the *Hebrews, because Egyptians never eat with foreigners. v33 The brothers were sitting as Joseph directed. The oldest brother sat at the head of the table. That was his right because he was the oldest son. And the youngest brother sat at the other end. And the brothers looked at each other in great surprise. v34 A servant took shares to them from Joseph’s table. But Benjamin’s share was 5 times bigger than the share of the other brothers. So they ate and drank with Joseph.