Robert founded the importance of his fief by marrying Gaitelgrima, daughter of Guaimar IV of Salerno and Drogo of Hauteville, the two most powerful south Italian lords of the day.
His daughter, Theodora, married Pandulf (or Landulf), lord of Capaccio (1040–1052), son of Guaimar III of Salerno and Gaitelgrima and brother of Guaimar IV, with whom he was assassinated.