The male Human merchant named Saun Dann asserted that he possessed a sibling when attempting to stop a brawl between an Imperial technician and the Wookiee Mallatobuck. He further stated that this sibling had a son serving within the ranks of the Imperial Military.
It remains ambiguous within The Star Wars Holiday Special if Saun Dann's claims regarding a sibling and nephew are genuine, or merely fabrications intended to divert the technician's attention. It's important to remember that he also shares other improbable stories with the Imperials as a means of distraction.