The young royals will have starring roles as page boy and bridesmaid.
Mia Tindall, Zara and Mike Tindall's eldest daughter, will take up the same position. That means Queen Elizabeth along with Prince Philip, Prince Charles and the rest of the royal family will be there for Princess Eugenie's very special day. Princess Eugenie is godmother to Maud.
Bride-to-be Princess Eugenie of York (left), along with her sister Beatrice, is unhappily famous for wearing peculiar hats, with the flamboyant numbers they picked for Prince William's wedding making a particularly lasting impression.
Prince George, five, will be joined by fellow page boy Louis de Givenchy - the six-year-old son of JP Morgan banking executive Olivier de Givenchy and his wife Zoe.
Eugenie and Jack got engaged in Nicaragua while on holiday at the beginning of 2018. Although Camilla is not Eugenie's blood-related aunt, she's definitely a close member of the family, but has chosen not to attend Eugenie's wedding at Windsor Castle. Mr Brooksbank is now manager of Mahiki, a nightclub in Mayfair but before that, he worked at Chelsea's Admiral Codrington pub, then the Markham Inn.
Arbiter added: "Royals often miss family events for pre-scheduled engagements".
Once the service has ended, the newly married couple will undertake a short carriage procession through part of Windsor High Street.