Hadad here and in 1 Chronicles 1:50 is the well-known Syrian name, of which Hadar (margin) is an accidental corruption, consequent on the close resemblance between “d” (daleth) and “r” (resh) in Hebrew, the final letters of the two names.
Related Commentaries of 1 Chronicles 1:30
1 Chronicles 1:30
30 Mishma, and Dumah, Massa, Hadad,e and Tema,