According to the outrageous report, first published by GLOBE in 2012, Charles' 19-year-old bride was forced to have her eggs harvested and fertilised with the Prince of Wales' sperm to "make sure they could produce royal heirs."
The eggs were "supposed to be destroyed" GLOBE claims, but a member of the medical team "stole an embryo and implanted it in his wife."
Sarah and Meghan reportedly met earlier this year, on the final day of the Royal Tour of Australia, Fiji, Tonga and New Zealand.
"The meeting was too brief but they got along tremendously," an insider revealed to GLOBE.
"They only got to chat for 41 minutes because Meghan had to be back before her absence was noticed," adds the source.
GLOBE claims during the meet-up, Sarah warned Meghan to "not trust" Charles.
Sarah also reportedly met Prince William's wife Kate Middleton in America, shortly after their marriage.
The Royal Family is yet to respond to GLOBE's sensational report.
Rumours surrounding the possibility of the late princess giving birth to a secret daughter have been swirling for years, but following Prince Charles 70th birthday celebrations, it looks as though those rumours are set to resurface – an event that has left him and his wife Camilla Parker Bowles furious.
For a number of years royal insiders have heard wild rumours that Diana gave birth to a girl called Sarah, who is now in her 30s and is said to be older than Prince William, 36.
Although the story has been dismissed as a preposterous rumour, the fact it’s doing the rounds again – and at a time when the limelight should be solely on Charles – has left a jealous Camilla furious.
“Camilla can’t believe that this story has reared its ugly head again on the eve of Charles’ 70th birthday,” says a source close to the duchess told New Idea. “She’s absolutely furious.