Her father was Paul-Annik Weiller (1933-1998), the first son of the aviator Paul-Louis Weiller of the Javal family and Miss Europe 1930 Aliki Diplarakos.
Sibilla has three surviving sisters: Aliki Béatrice Victoria (1967), married to André Aranha Correia do Lago; Cosima Marie Elisabeth Edmée (1984); and Domitilla Louise Marie (1985).