A moment to remember - Siblings Princess Madeleine, Prince Carl Philip and Crown Princess Victoria with fiancé Daniel sharing a laugh as they arrive for the Swedish Government's dinner on the eve of Victoria and Daniel's wedding, June 18, 2010.
The Casiraghi Trio and their nestling - Siblings Andrea, Pierre and Charlotte Casiraghi with their youngest sister Princess Alexandra pictured in Monaco in November 2009.
March 26, 2011 - Sheikh Hamdan gives a flower to his sister Sheikha Al-Jalila during the Dubai World Cup. Jalila is the daughter of Sheikh Muhammad and Princess Haya.
Source: Laha Magazine
September 2006 - Princess Salma plays with her brother Prince Hashem.
May 2011 - Crown Prince Moulay Hassan and his sister Lalla Khadija pose for a picture released to mark the former's 8th birthday.
Princess Elisabeth, Prince Gabriël, Prince Emmanuel and Princess Eleonore picture at the royal garden.
Crown Prince Felipe and Princess Letizia's daughters Leonor and Sofia are photographed for the couple's Christmas card 2010.
Source: Det kongelige hoffs fotoarkiv
The picture shows Princess Ragnhild of Norway and her younger sister Princess Astrid in 1932.
I. ) The Netherlands
Canada, December 1944: Princess Margriet, Princess Irene and Princess Beatrix in Canada during the Second World War.