The friends-starved Duke and Duchess of Sussex have infuriated former pals David and Victoria Beckham by forming an alliance with the British power couple's estranged son Brooklyn and his American heiress wife – and it's just one of the secrets behind the growing Beckham family feud, RadarOnline.com can reveal. Critics tell us the battle royal is also Prince Harry and spouse Meghan Markle's shot across the bow at his brother, Prince William, who has warmly embraced the Beckhams after their dramatic falling-out with the Sussexes. "Victoria Beckham is probably saying, 'Why don’t they mind their own business? What do the Sussexes know about family?'" a Hollywood insider told RadarOnline.com, referring to Prince Harry and Markle's strained relationship with his kin. "This is like a perfect storm. We have Meghan, a pot-stirrer, on one side, and we have Victoria, who is this explosive dynamite declaring war on the Sussexes. Victoria is very sensitive about her family and easily angered, so there is a lot going on here."Tangled WebSources say the Beckham fam's feud further flared when Brooklyn and his wife of three years – Bates Motel actress Nicola Peltz – skipped soccer legend David's star-studded 50th birthday bash in Miami. Rumors blame the beef on the allegedly frosty relationship between Peltz – daughter of billionaire businessman Nelson Peltz – and her mother-in-law. But our insiders added by that point the Sussexes – who are said to have lost the support of many celebs in Hollywood – had already charged into the fray, and Brooklyn, 26, and Nicola, 30, were invited to a dinner party at the California home of a neighbor to the duke and duchess. Sources claim David and one-time Spice Girl Victoria, 51, were shocked by the news because they'd severed ties with the Sussexes after being accused of leaking stories about Markle to the press.Insiders close to the Sussexes have denied there were any ulterior motives and insist the pair did not host the get-together or personally extend the invite. However, one royal expert believes Harry, 40, and Markle, 43, may be befriending the younger couple to irritate not only the Beckhams – but also William, 42, and his wife, Kate Middleton, 43. The insider told RadarOnline.com, "It's like a big 'f--- you’ to William and Kate because they are close with the Beckhams." Meanwhile, future queen Middleton, the Princess of Wales, appeared to make a statement by stepping out in an olive suit designed by Victoria's self-named label.Official word from Kensington Palace is Middleton wore the outfit to demonstrate her support for U.K. fashion houses, while presenting the Queen Elizabeth II Award for British Design. However, the influential princess has rarely worn clothing by Victoria for official engagements. A source said: "I think she was sending a clear message of support to Victoria Beckham." Another added: "The royals getting involved in this is a sign that this feud is only gonig to get more complex and deeper by the day."