According to Express, Prince William - who shares Prince George, Princess Charlotte and Prince Louis with Kate - has a zero-tolerance policy on breaches of confidence, with one friend saying "You can forget it if you abuse his trust."
The publication also reported that there was a tense argument over the Royal Family’s 2018 Easter service at Windsor Castle’s St George’s Chapel.
The York sisters allegedly snubbed the Duke and Duchess of Cambridge, then disrespected Queen Elizabeth and had to be told to “show some respect”.
A royal insider said last year: “Things were so bad, Eugenie and Bea wouldn’t even stand with Wills and Kate after the service.”
The source added: “Kate knows that Bea and Eugenie can be troublemakers and is trying to keep them at arm’s length from Meghan.”
WATCH: Kate Middleton says she was nervous to meet Prince Charles
One insider also told The Daily Mail in 2016: “Royalty is all about pecking order, often in a cruelly blunt sense, and it is Kate who has all the toys and the position.
“Despite being the only young ‘blood Princesses’, Beatrice and Eugenie have been reduced to walk-on parts in Royal Family life.
“It particularly hurt when Kate did solo engagements with the Queen during the Diamond Jubilee. They felt snubbed.
"Their father sometimes takes up the cudgels on their behalf — for example, when they lost their paid-for royal protection officers.
“But while the Queen is too old to make a fuss or rock the boat, Charles remains determined to have a smaller task force, namely himself, his own offspring and their families."