The A and the B list intrigue me. The Duke and Duchess of Bragança, the Prince and Princess of Piemonte, Prince Alexander and Princess Katherine of Serbia, Princess Margarita and Prince Radu of Romania... all of them were on the A-list.
The Duke and Duchess of Parma (Chef of the House Bourbon-Parma, of which Jean, Henri and Guillaume consider themselves Princes of) as well as Prince Georg-Friedrich and Princess Sophie of Prussia were examples of the royals on the B-list.
I can not find a clear line in that policy. The Chambre des Députés was a relatively small banqueting venue, this caused these somewhat painful divisions i.m.h.o.