The Duke and Duchess of Parma were not on the A-list (grand diner in the hall of the Chambre des Députés) but on the B-list (diner in a cultural centre).
When the diner in the Chambre des Députés was finished, the B-list guests were transpoted to join the guests from the A-list (between 22.00 and 23.00 o'clock) so chance that they were missed by the photographers. There must be pictures however, I am sure these will pop up.