The sons of Bela were Addar, and Gera, and Abihud. The first of these is thought to be the same with Ard, mentioned among the sons of Benjamin, Genesis 46:21 but was one of his grandsons, see Numbers 26:40 as Gera also was.
Related Commentaries of 1 Chronicles 8:3
1 Chronicles 8:3
3 And the sons of Bela were, Addar,a and Gera, and Abihud,