Trademarks can provide a lucrative revenue stream for sports stars and generate significant income for their families long after the athletes’ deaths. Conflicts over trademark rights usually erupt between an athlete’s family and businesses seeking to capitalize on a player’s brand. But one ongoing legal battle over a deceased athlete’s trademark pits the family of the late National Baseball Hall of Famer Roberto Clemente against the U.S. territory of Puerto Rico.Clemente’s three sons are appealing the dismissal of their …