According to the publication, while advising Meghan to shun her estranged father Thomas Markle to 'protect Harry from humiliation', Camilla is 'quietly stirring the pot.'
The palace insider insists to GLOBE the duchess is encouraging Markle, a retired Hollywood lighting director, to make embarrassing public appeals for a reunion with his daughter.
Meanwhile, the insider also says Camilla is leaking dirt on Meghan's father to other outlets.
'Leave it to Camilla to know how to push buttons,' a royal insider tells GLOBE.
'She is encouraging Thomas to continue his embarrassing public outbursts that make him even more toxic to Meghan and the royals.'
At the same time, the Duchess of Cornwall is telling Her Majesty that the Duchess of Sussex is 'unworthy' of royal life, GLOBE says.
This is not the first time palace insiders have claimed Camilla has plotted against Harry's new wife.
Behind the scenes of Harry and Meghan's spectacular May 19 wedding, palace sources told New Idea a series of intense arguments, in the lead-up to the wedding and in the days that followed, marred the joyous occasion, causing tension among senior members of the royal family.
Central to the drama was Camilla who tried her very best to sabotage Harry and Meghan’s big day – forcing the former actress to stand her ground against her new mother-in-law.
It’s believed Camilla’s dislike of Meghan had been brewing for some months, but became worse in the week before her wedding to Harry due to the dramas with her father Thomas.
‘Camilla was absolutely appalled that the royal wedding turned into an episode of Jerry Springer in the week before the big day,’ says a palace source.
‘She’s always had her reservations about Meghan marrying into the royal family, believing that she wasn’t “regal enough” for Harry and did everything she could to talk him out of going through with the wedding. So when Meghan’s dad was exposed for cashing in on his daughter’s wedding, it only strengthened her belief that Meghan didn’t belong in the palace and that her trailer-park family were bringing the whole monarchy into disrepute.
‘Camilla wasn’t backward in telling Meghan and Harry exactly how she feels. And while Harry has always stood up for Meghan and done his best to shield and protect her from Camilla’s attacks and bitterness, Meghan decided to take matters into her own hands this time and take a firm stand.
'So it was pretty intense to say the least.’
Insiders also told New Idea at the time that the situation escalated when Meghan’s mum Doria arrived in London for the wedding.
Jealous that her husband Charles had taken Meghan’s mum under his wing and gone to great lengths to make her feel welcome, Camilla became even more livid when the royal-to-be asked the Prince of Wales to walk her down the aisle.
However, at the time Meghan fought back against her new stepmother.
GLOBE claimed at the time the pair went head-to-head in a shocking showdown just days after the royal wedding, with the new duchess confronting Camilla and convincing Harry to 'shun her.'
'Palace insiders knew this was coming,' a royal watcher told GLOBE. 'Meghan has smiled and turned the other cheek as Charles and Camilla desperately tried to break her and Harry up and stop the wedding.
'But they targeted the wrong person!' the insider explosively claimed.
The royal insider further spills, 'Meghan is a strong, independent former actress! She was warned royal palaces are breeding grounds for jealousy, suspicion and hostility and she won't let anyone smear her reputation.'
'I'm told the gloves came off in minutes!'
The royal family is yet to respond to GLOBE's report.