The sisters of Charles Allen McClain died very young and he had no other siblings. He said that he was an only child so they may have died before he was born.
Ancestry.com has the WWI record of Charles posted and his sons were also military but there are no surviving males in this line.
His son Joe was in Pearl Harbor; was married to a Broadway but had no children.His son Charles had only one daughter and the other son Walton is buried at Arlington.
Elizabeth Broadway is found on 1860 census with parents Abner and Susan Broadway.Elizabeth later married John Gardner in Ramer after the loss of Josiah.In 1910 she is found with John,and Charles with his new bride in same household.
Elizabeth's sister Rebecca Broadway married Clopton Gibson who's family also came from South Carolina.