This Christmas, Prince William’s ‘secret’ step-sister will be joining the Royal Family – but their relationship hasn’t always been so cosy.

This year’s annual festivities in Sandringham will reportedly include some 45 attendees. Prince William himself let the number slip during a festive gathering in Wiltshire for the families of the 1st Battalion Mercian Regiment.

“We’ll be in Norfolk, at Sandringham. We’ll be 45 for Christmas. It won’t be quiet, it will be noisy.”, he shared.

Of course, the most senior members will be seated at the table, including King Charles, Queen Camilla, the Prince and Princess of Wales, Anne, Princess Royal, and the Earl and Countess of Wessex. Not to mention the numerous young royal cousins who’ll no doubt be enjoying all the fun and excitement of the day.

Queen Camilla’s daughter Laura Lopes has also received an invite, signifying a healing of alleged past anger on both sides of the blended family…

This marks the second time that Laura, 46, an art curator, has joined the royals for Christmas – the first time being last year. She and her elder brother Tom Parker Bowles, 49, were welcomed during Camilla’s first marriage to Andrew Parker Bowles, 84, with Laura arriving on New Year’s Day 1978.

Mum-of-three Laura has a passion for art. She studied Art History with Marketing at Oxford Brookes University before founding the fine art gallery Eleven in 2005. That same year, Laura’s life changed forever when King Charles married her mother, Queen Camilla, in a civil ceremony that was held close to Windsor Castle.

The much-talked-about union meant that she and food writer Tom were now step-siblings to Princes William and Harry, and the newly forged bond wasn’t always easy. Though they were seen laughing together at the April 2005 ceremony, it’s been reported that William and Laura would have “terrible fights”.

In the 2010 book Harry and William, author Katie Nicholl wrote:

“William and Laura used to have terrible fights over who was to blame for their broken homes. William would blame Camilla for all the hurt she had caused his mother [Princess Diana], which would send Laura into a rage. Laura was not having any of it. She would take a hard line and fire back at William, ‘Your father has ruined my life’.”

Laura married chartered accountant Harry Lopes in 2006 in a Wiltshire ceremony attended by Princes William and Harry. Like her mother, Laura chose Anna Valentine for her wedding gown, which she finished off with a diamond-encrusted tiara – a family heirloom the now-Queen Camilla wore during her first walk down the aisle.

A former Calvin Klein model, Harry also has aristocratic roots, meaning he’ll likely fit in around the Sandringham dinner table. According to Hello! magazine, Harry’s is the grandson Massey Lopes, 2nd Baron Roborough, and will one one day inherit both Gnaton Hall in Devon and Skelpick Estate in the Scottish Highlands.

Laura and Harry went on to welcome daughter Eliza, 16, and twins Gus and Louis, 14, who will all be welcome at the upcoming gathering. The children’s presence at various high-profile royal events would suggest that tensions have thawed somewhat over the years.

At Prince William and Princess Kate’s 2011 wedding, Eliza was chosen as a bridesmaid. Her stepfather, King Charles, was seen lifting her up on the balcony of Buckingham Palace to wave at the exuberant crowds below. Gus and Louis were also appointed as Pages of Honour during the Coronation of King Charles and Queen Camilla, alongside their step-cousin, Prince George.

This comes as the family prepares for its grandest Christmas in some time, surrounding themselves with loved ones after what has been a difficult year. “After the year they’ve had, I’m sure it’s going to mean the world to the King and Queen to have as many of their family as possible joining them for Christmas. And, as the number of youngsters increases, so the celebrations become more and more child oriented. Which is exactly what Christmas should be all about.”, Former BBC royal correspondent Jennie Bond told OK!