Princess Charlotte is set to begin spending a lot less time with her brother, Prince George, due to a strict royal rule.
Charlotte, nine, and future King of England, George, 11, are often pictured looking joined at the hip, but will be forced to separate soon, it is believed.
George is the second in line to the throne.
The young boy's reign is likely to start well into the future, as his father, Prince William, will ascend to the throne first following King Charles.
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As George is set to turn 12 next year, it is thought that should the royals stay true to a longstanding tradition, then George's birthday in July 2025 will mark a new era, where he will be required to travel separately from his sister Charlotte, brother Louis, and his parents on royal visits and tours.
As the royals are often making an appearance at a variety of events and engagements, it's likely that there will be a lot of travel to undertake in the coming year, and George will not be able to travel alongside his family - something which is likely to sadden his little sister.
The reason for this is that two heirs to the throne are not permitted to travel together in the heartbreaking event of a tragedy - for example, a plane crash.
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By keeping the heirs separate, it ensures that should something go terribly wrong, there is still somebody who can reign for England, thus protecting the monarchy.
Prince William himself had to go through the same process once he turned 12.
Graham Laurie, King Charles' former pilot, told OK! magazine: "We flew all four: the Prince, the Princess, Prince William and Prince Harry, up until Prince William was 12 years old.
"After that, he had to have a separate aircraft and we could only fly all four together when they were young with the written permission of Her Majesty.
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"When William became 12, he would fly normally in a 125 from Northolt and we would fly the 146 out with the other three on."
The rule has persevered for decades, and sadly isn't without reason.
Various members of the royal family have fallen victim to air incidents throughout history.
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Prince Philip's sister Princess Cecilie died in an air accident in 1937. Queen Elizabeth II's uncle Prince George was also killed in a similar incident in 1942, followed by the Queen's cousin, Prince William of Gloucester, in 1972.
Notably, the rule can be changed by the monarchy at any given time, meaning King Charles or Prince William may change their minds about the requirement in the future.
Prince William flew with his entire family in 2014 during the family's Australian tour.
He told BBC's Newsround: "They had to ask the Queen for permission, but she said yes."
Topics: Prince George, Prince William, Royal Family
Kya Buller