Prince George, Princess Charlotte and Prince Louis Have New Names Under King Charles III

Prince George, Princess Charlotte and Prince Louis have new surnames.

On Friday, King Charles III addressed the United Kingdom for the first time since Queen Elizabeth II died at the age of 96. Among the changes announced, Charles, 73, shared that Prince William, 40, and Kate Middleton, 40, have inherited the titles of Prince and Princess of Wales.

Their three children — who are now the second, third, and fourth in line to the throne — go from being Princes and Princess of Cambridge to being Princes and Princess of Wales. Therefore, they are now Prince George of Wales, Princess Charlotte of Wales and Prince Louis of Wales.

PA From left: Prince George, Kate Middleton, Prince Louis, Prince William and Princess Charlotte

The children were previously known as George Cambridge, Charlotte Cambridge and Louis Cambridge at school. Now they will be known to their friends and teachers as George Wales, Charlotte Wales and Louis Wales.

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The change comes as all three siblings started at their new school, Lambrook, this week following their family move out of London over the summer. The family of five now lives in Adelaide Cottage in Windsor.

RELATED: King Charles Officially Names William and Kate Prince and Princess of Wales

PA Prince George, Kate Middleton, Prince Louis, Prince William and Princess Charlotte

"Today, I am proud to create him Prince of Wales, Tywysog Cymru, the country whose title I have been so greatly privileged to bear during so much of my life and duty," Charles said during his address. "With Catherine beside him, our new Prince and Princess of Wales will, I know, continue to inspire and lead our national conversations, helping to bring the marginal to the centre ground where vital help can be given."

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Max Mumby/Indigo/Getty Prince William and Kate Middleton with Prince George, Princess Charlotte and Prince Louis

As William and Kate take on their new titles, a royal source told PEOPLE the couple is focused on "deepening the trust and respect of the people of Wales over time."

"The Prince and Princess of Wales will approach their roles in the modest and humble way they've approached their work previously," the source added.

As Kate Middleton takes on the title of Princess of Wales, which William's mother, the late Princess Diana, once held, a royal source told PEOPLE: "The new Princess of Wales appreciates the history associated with this role but will understandably want to look to the future as she creates her own path."

Samir Hussein/WireImage Prince George, Prince Louis and Princess Charlotte

In accordance with the royal line of succession, Charles takes the throne, to be followed by William, who will now be followed by George, 9. Next comes 7-year-old Charlotte, followed by youngest sibling Louis, 4. Prince Harry becomes fifth in line to the throne.

Charlotte's spot in the royal line is due to a 2013 succession law that allows the crown to pass on in order of birth regardless of gender. (Up until then, succession rules stated that the crown would pass to the eldest male heir and only to a female heir when there were no other male heirs available.)

"That might seem like a minor thing, but it is a big victory for equality," Williams previously said of the amendment. "It says to people, which [the Queen] proved more than anyone, that a monarch is a job and a woman can do it just as well as a man."