According to The Times, Prince Harry has asked his grandmother to make an exception for his wife-to-be as there is an unwritten rule of no un-married partners or fiancees coming to Christmas.
"Now they are engaged it was unthinkable they would be apart for Christmas. The Royal Family have fully welcomed Meghan into the fold," a friend of Harry's told The Express.
According to royal commentator Richard Fitzwilliams, Christmas at Sandringham will serve as the ultimate training for Meghan as she prepares to become a full-time royal.
"Kate was a bag of nerves the first time she did Christmas with the royals, so she knows exactly how daunting it must be for Meghan," the source said.
Christmas with the royals is a serious production and every item on the agenda runs to a perfectly-time schedule.
The newly-engaged couple are set for a jam-packed calendar of festive celebrations kicking things off with a black-tie dinner on Christmas Eve with key royal family members including Prince Charles, Duchess Camilla, The Queen, Prince Philip, Prince William and Duchess Catherine.
WATCH: Meghan and Harry make at their first royal engagement together. Post continues...
“Now they are engaged and she will shortly be a senior member of the royal family, it is pivotal that she feels an integral part of it as soon as possible," he revealed.
“Kate and the younger members will help her through the strict protocol of the royal festive celebrations which take place over three days and which can be daunting.”
An insider revealed to Closer Magazine last week that Duchess Catherine has stepped up to help her future sister-in-law and show her the ropes.
Cheap and cheerful presents are swapped on Christmas Eve - with a focus on humorous gifts instead of material. If Meghan is racking her brain as to what to get The Queen, Duchess Catherine has previously revealed she made her chutney!
Christmas morning starts with a full English breakfast before heading to church for a morning service at St Mary Magdalene, followed by a 50-minute lunch, before gathering around the TV to watch The Queen's Christmas message at 3pm, and a round of pheasant shooting on Boxing Day.
But even the royals indulge in the silly season and they reportedly enjoy popping open bespoke Christmas crackers (everyone rocks the colourful hats except for Her Majesty), party games and charades.
It's believed Meghan and Harry will head to America after Christmas in the UK to spend time with Meghan's mother Doria Radlan. Perhaps they'll also squeeze in a visit to Meghan's father Thomas Markle.
As wedding preparations get underway, Meghan's uncle has confirmed to The Sun that Meghan's reclusive father Thomas Markle will walk his daughter down the aisle at St George's chapel at Windsor Castle next May.
"I know Thomas feels happy and excited about the engagement. He and Meghan have a good relationship, and they talk weekly so she keeps him up to date," Thomas' brother Michael from Palm Bay Florida told the publication.