Further research showed that it was, in fact, a great-great-grandson who may or may not have been extremely wonderful.
In another comma-vs.-hyphen incident, I changed a headline from Controversial Ad Links MLK-GOP to Controversial Ad Links MLK, GOP, only to see something about an MLK, GOP Link in the Web hed on the same story. There's where the hyphen belonged.
To review, a comma can stand for "and" in a headline. The hyphen (or en dash, for publications that use the en dash) is the convention for a "between" link in an adjectival construction. Ali, Frazier Fight? They did indeed if you mean "fight" as a verb, but that fight (n.) was the Ali-Frazier Fight. (And so were the other two, though I suppose the first one was more properly the Frazier-Ali fight.)