[5] This would establish the kings of Naples and Sicily as cadet members of the Spanish royal family, and so the country enjoyed strong relationships with its 'mother state', following many of its legal customs.

The Act of Cannes states: Before Us, Don Alfonso de Borbón, Count of Caserta... Head of the Royal House and Dynasty of the Two Sicilies... His Royal Highness Prince Don Carlos, our beloved Son, appears and declares that, preparing to marry HRH Infanta María de las Mercedes, Princess of Asturias, and assuming by such marriage the nationality and quality of Spanish Prince, undertakes to renounce by this Act and solemnly renounces, for himself and for his heirs and successors, all the right and reason to the eventual succession to the Crown of the Two Sicilies and to all the assets of the Royal House that are in Italy and elsewhere, and this according to our Laws, constitutions and Family customs, in execution of the Pragmatic Sanction of King Charles III, our Augustus ancestor, of October 6, 1759, the prescriptions of which he freely and spontaneously declares to subscribe and obey.

He also declares, in particular, to renounce for himself, his heirs and successors to the assets and values existing in Italy, Vienna and Monaco (Bavaria) and destined by His Majesty King Francis II (may God have welcomed his soul), to the foundation of a majorat for the Head of the Dynasty and of the Family of the Two Sicilies and for the constitution of an endowment fund in favor of the Royal Princesses and granddaughters of our August Father King Ferdinand (may God have welcomed his soul), of marriageable age; but preserving his rights to the part of the assets that were bequeathed to him by his late uncle King Francis II, in the event that the Italian Government, which improperly retains them, makes the due restitution and the same everything that may arrive to him by other testamentary legacies.Supporters of the other claimant to the headship of the House of Bourbon-Two Sicilies, sometimes referred to as the Castrist faction, argue that because Prince Carlos signed this agreement, he relinquished all of his rights and those of his descendants to both the headship of the family and the Sacred Military Constantinian Order of Saint George, and so the rights currently fall on Prince Carlo, Duke of Castro.

However, supporters of Pedro, also known as the legitimists, argue that the Act of Cannes was subject to a condition that never arose and its terms would have only applied if Prince Carlo's wife had inherited the throne of Spain, and he had become king of the Two Sicilies, which never happened and was furthermore highly unlikely at the time the document was created.

Regardless, the Papal Brief of 1698 and Bull of 1718 established that the grand mastership was not tied to any temporal sovereignty but was a separate inheritance of the Farnese family, and so it is the mainstream academic view that succession is not linked to the throne of Naples and Sicily.