He was the eldest son of
Ugo, 4th Duke of Sora and Duchess Maria Ruffo di Bagnara. He married Giustina Gallio (29 October 1644 – 21 July 1679) and then, when she died, he married
Ippolita Ludovisi on 19 October 1681. The
Boncompagni-Ludovisi union lasted until the
French Revolution and included the development of the
Archivio Boncompagni-Ludovisi held by
The Vatican. Gregorio and Ippolita had six children: • Hugo (1684–1686) died young •
Maria Eleonora (1686–1745), Princess of Piombino, married her uncle and Gregorio's brother
Antonio I Boncompagni • Constance (1687–1768), married Vincenzo Giustiniani, Prince of Bassano • Maria Teresa (1692–1744), married
Urbano Barberini, Prince of Palestrina • Giulia (1695–1751), married
Marco Ottoboni, Duke of Fiano • Anna Maria (1696–1752), married
Gian Vincenzo Salviati, Duke of Giuliano ==References==