These are those who came from Tel Melah, Tel Harsha, Kerub, Addon, and Immer. They weren’t able to prove their ancestry, whether they were true Israelites or not:
The sons of Delaiah, Tobiah, and Nekoda, 642.
Likewise with these priestly families:
The sons of Hobaiah, Hakkoz, and Barzillai, who had married a daughter of Barzillai the Gileadite and took that name.