Meghan Markle's mother, Doria Ragland, would have been invited by the Queen to spend Christmas with the royal family in Sandringham.
Doria, 62, the only member of Meghan's family to attend the wedding to Prince Harry at Windsor Castle in May, would have been called a "mark of respect."
According to a report in the Sunday Express, a source said it was a "very thoughtful gesture" for the pregnant Duchess.
The move is unprecedented since a member outside the royal family was not invited to stay on the Norfolk estate during the previous Christmas period.
Kate Middleton's family joined royalty in the church on the previous Christmas morning, but remained in nearby Anmer Hall rather than Sandringham itself.
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It is said that the source said that the Queen's invitation showed respect and acknowledged that Meghan would be spending Christmas away from the family in Britain.
A spokesman for Buckingham Palace has so far declined to comment.
After weeks of drama around Meghan's father, Thomas Markle, and their extended and separated family members in the United States, Doria was praised for her elegant and graceful appearance at the royal wedding.
Mr. Markle had to walk with his daughter down the hall, but gave up at the last minute after it emerged that he had staged paparazzi photos in the days before him.
He later said that he apologized to Harry and Meghan and denied the realization of the money shots, insisting that they were taken in an attempt to "change their image."
Doria joined her daughter at an outdoor reception at Kensington Palace in September to mark the launch of a charity book to help those affected by the fire at Grenfell Tower.
The Duchess, who worked with Grenfell's activists on the book, Together, said it was a "labor of love."
Doria introduced herself to the guests of the day as "Meg's mother."
She allegedly said she was "upside-down" with pride while Meghan helped prepare the luncheon for the guests.
Meghan and Harry have recently returned to the UK from their gigantic Commonwealth tour and will spend their first Christmas together as husband and wife in December.
