They were all family leaders among their father's descendants. Shimei was the father of Shelomoth, Haziel, and Haran.
Later, Shimei had four more sons, in the following order: Jahath, Zina, Jeush, and Beriah. But Jeush and Beriah didn't have many children, so their descendants were counted as one family.
Ladan was the father of Jehiel, Zetham, and Joel.
Ladan, Ammihud, Elishama,