Meghan, Duchess of Sussex's estranged half-sister has challenged the former actress over claims they were never close.
During her TV interview with Oprah Winfrey, which aired in America on Sunday night, Meghan poked fun at the tell-all book her father's other daughter, Samantha Markle, wrote about the sisters' relationship - and claimed they never really had one.
"I think it would be hard to tell all when you don't know me," the Duchess told Oprah when asked about Samantha's book, The Diary of Princess Pushy's Sister Part 1. "I grew up as an only child... The last time I saw her (Samantha) must have been at least 18, 19 years ago, and before then, 10 years before that."
Meghan went on to claim Samantha only changed her last name back to Markle when she started dating Prince Harry, adding, "I think that says enough."
A day after the explosive interview aired in the U.S., Samantha spoke to Inside Edition, stating, "I don't know how she can say I don't know her and she was an only child. We've got photographs over a lifespan of us together. So how can she not know me?"
Samantha showed photographs of her and young Meghan throughout the years, including one she insists was taken 13 years ago at her college graduation in 2008. She also maintained that she changed her name back to Markle many years ago and it had nothing to do with her sister.
"I was a Markle before she was," she said. "I thought that was kind of weird that she would say I only changed my name back when she met Harry. Markle has always been my name."
During her interview with Oprah, Meghan also confirmed she and her father, Thomas Markle, had become estranged after he lied to her about talking to the media and handing over a letter she wrote to him just before her royal wedding.
He will appear on U.K. show Good Morning Britain on Tuesday to respond to his daughter's talk with Oprah.
The show's co-host, Piers Morgan, confirmed the news in a tweet on Monday, which read: "UPDATE: Meghan Markle trashed her dad on US TV today. On tomorrow's @GMB, Thomas Markle will give his first exclusive interview in response (sic)."