'Sister' in the Bible

Now Hadad was very pleasing to Pharaoh, so that he gave him the sister of his wife, Tahpenes the queen, for his wife.

And the sister of Tahpenes had a son by him, Genubath, whom Tahpenes took care of in Pharaoh's house; and Genubath was living in Pharaoh's house among Pharaoh's sons.