Samantha Markle has told More FM's Polly and Grant she thinks Prince Harry should not have allowed Meghan Markle to act so "recklessly" in her role in the royal family.
The Kiwi radio hosts interviewed The Duchess of Sussex's outspoken older sister on Friday morning, and she told them she felt Meghan and Harry had "done a lot of damage".
Samantha said she wasn't entirely surprised by the couple's bombshell announcement about stepping back from the royal family because she felt they had been on a "crash course for some time".
"What I was surprised about was that I thought my sister would sort of mellow out in the role, learn, be disciplined, do her due diligence and really honour and support her role as she had taken it on," Samantha said.
"She entered it knowingly and willingly. I'm surprised at what I feel was recklessness."
Broadcaster Polly Gillespie then asked Samantha if she thought Meghan could have had the influence to sway a "strong-willed" man like Harry.
"I don't think he's that strong-willed, or perhaps he wouldn't have allowed such disaster within the royal family with whom he's been so close," Samantha replied.
"I feel perhaps he should have taken the reins much earlier and made sure this fallout would never happen and sort of kept a bridle on her as his new wife."
Samantha also made mention of her and Meghan's father, Thomas Markle, who has also been speaking to the press.
She said that her dad had been getting a lot of "moral support" after his damning Channel 5 documentary, but also that he was "over his broken heart".
"He realises, you can love your children and that doesn't mean that they're going to reciprocate, you can give them everything and be there for every nuance of their life and that doesn't mean that they're not going to make deviant choices that you don't expect, and you have to deal with that," she said.
For her part, Samantha said if the couple ends up happy, "great for them"; but added that she felt they had "done a lot of damage in their wake".
The 55-year-old finished by saying she'd love to come to visit New Zealand one day soon.