She is the widow of Rodrigo de Belsunce d'Arenberg who was the son of a Henri, Marquis de Belsunce and his wife Marie-Therese who married the 11th Duke d'Arenberg after the death of her first husband. The duke later adopted his wife's son Rodrigo and daughter Laetitia. Laetitia married Leopold of Habsburg-Toscana and is the mother Archduke Sigismund, Grand Duke of Toscana.I am not sure if she is a princess of Arenberg, she uses the last name 'della Giovampaola' before Arenberg and I can not find her in the family genealogy:
https://gw.geneanet.org/frebault?lang=en&m=N&v=d+arenberg