Eliezer’s sons were Rehabiah, first; Eliezer did not have any other sons, but Rehabiah’s sons were very numerous.

From Rehabiah:
from Rehabiah’s sons: Isshiah was the first.

His relative through Eliezer: his son Rehabiah, his son Jeshaiah, his son Joram, his son Zichri, and his son Shelomith.