Shema was the father of Raham the father of Jorkeam, and Rekem was the father of Shammai.
The text about Caleb appears tangled in our version: he is called father of Hur in one place and son of Hur in another. The latter passage has been copied wrong and should read 'Hur the son of Caleb.' Azubah was his wife; Jerioth was a secondary wife, mother of those children named.
AI summary
Commenting on 1 Chronicles 2:18-55
The genealogy here is deeply obscure. The collocation of 'sons of Mareshah the father of Hebron' is very strange; Hebron must mean the city, yet the continuation names Korah, Tappuah, Rekem, and Shema as Hebron's sons, and the verb 'begat' plainly denotes human propagation, not lordship of cities. The text resists easy resolution.
AI summary
Commenting on 1 Chronicles 2:42-45
Salma the father of Bethlehem,.... Or prince of Bethlehem, as the Targum; not the same as in Ch1 2:11 he was the son of Nahshon, this of the younger Caleb: Hareph, the father of Bethgader; prince of a place of that name called Gedor, Ch1 4:4, and where this man's name is Penuel; Gedor was in the tribe of Judah, Jos 15:58.