Francesco Pacelli (February 1, 1872 – April 22, 1935) was an Italian lawyer and the elder brother of Eugenio Pacelli, who would later become Pope Pius XII. He acted as a legal advisor to Pope Pius XI; in this capacity, he assisted Cardinal Secretary of State Pietro Gasparri in the negotiation of the Lateran Treaty, which established the independence of Vatican City.
Doesnt say, he is the younger brother of Francesco Pacelli so he could be the youngest