William Tiffany's relation to the jewelry family

Does anyone know exactly how William Tiffany was related, if at all, to the Tiffany family of Tiffany & Company jewelers?

According to Wikipedia, he wasn't a direct descendant of Charles Lewis Tiffany who founded Tiffany & Company, as Charles had only one son, Louis Comfort Tiffany who branched off into stained glass design. Louis had several daughters but only two sons, one of whom died in infancy and both of whom were named Charles Louis Tiffany. (The surviving son was approximately William's age.) The closest William could have been related was a nephew or great nephew of Charles Lewis and a cousin of Louis Comfort, although contemporary obituaries identified him as a member of the jewelry family.

BTW, as I pointed out in an entry in the Goofs section, William Tiffany was not killed in action as a sergeant on Kettle Hill as depicted in Rough Riders, but survived the war and received a battlefield commission to Second Lieutenant, but tragically died of yellow fever; he barely hung on and made it home to New York to die.