Crown Princess Mary and Prince Frederik of Denmark pose in Greenland's traditional costume with their children on a commemorative stamp on October 18, 2016

Crown Princess Mary and Crown Prince Frederik appeared on a postal stamp following their wedding in 2004

Crown Princess Mary and Crown Prince Frederik are joined by their children Prince Christian, Princess Isabella and twins Prince Vincent and Princess Josaphine on a Greenland stamp commemorating their anniversary

Prince Vincent entertained his siblings when racing around on a wheeled office chair, while Princess Josephine looks on.

Prince Christian and Princess Isabella posed for this touching shot in their traditional Greenland dress

Pictured top row: Prince Vincent and Prince Christian and bottom row: Princess Isabella and Princess Josephine, the children are beaming as they swap traditional ceremonial outfits for the national dress of Greenland

HRH Prince Christian of Denmark turns 11 years old on October 15, 2016.

Then the couple appeared on a stamp once more to commemorate the birth of their son Prince Christian in 2005

Crown Princess Mary of Denmark with her children Princess Isabella of Denmark and Prince Christian of Denmark during a reception hosted by Queen Margarethe of Denmark for the Danish Olympic and Para-Olympic Teams at Christiansborg on October 14, 2016 in Copenhagen, Denmark.