If what insiders out of London are saying is true, there will be a Duke and Duchess of Sussex-sized gap on the guest list of Princess Beatrice's wedding to Edoardo Mapelli Mozzi next year.
"Tension has been brewing between Harry and Meghan and the York girls for months now," one palace source tells Woman's Day exclusively.
"Beatrice has confessed to friends that if she gets her way, they won't be invited."
It's believed the rift began when Beatrice's younger sister Princess Eugenie, 29, was privately miffed that Meghan, 38, debuted her baby bump during her own nuptials last October, effectively stealing her thunder.
And ever since then, it's been a social media tit for tat between the houses of Sussex and York.
"As soon as Harry and Meghan officially confirmed their pregnancy via Instagram as they began their tour to Australia days after Eugenie's wedding, you'll recall that her mum [Sarah Ferguson] dropped a treasure trove of Eugenie's wedding pics just hours after," our source adds. "It was obviously done on purpose as revenge."
WATCH: Did Prince Harry and Duchess Meghan have a fight at Princess Eugenie's wedding? Post continues after video...
And now, it seems the war has escalated again.
Just 24 hours after Meghan and 34-year-old Harry gave the world an incredible glimpse of their son, Master Archie, during their trip to South Africa, the Yorks struck again, sharing a picture of Edo and 31-year-old Beatrice showing off her brand new art deco-style diamond dazzler.
"The timing of Beatrice's announcement was incredibly rude, given it stole the spotlight back from the important causes Harry and Meghan were trying to promote," says a source. "Of course, they were furious, but it's the kind of pettiness they've come to expect these days."
And while it would ordinarily be protocol to invite senior royals to her wedding, friends say Beatrice, who began dating the real-estate entrepreneur just 11 months ago, may have found a way to sidestep the niceties.
"Edo's a private citizen, so technically she can forgo the traditional royal wedding for something low-key. That way she won't have to invite Harry and Meghan and worry about all eyes being on them instead of the bride and groom!"