Porter confirmed a letter had been sent to the magazine by Carter's lawyers, but stressed its contents were not a threat of legal action, "more a 'can we please just not do it again?'."
"There has been correspondence, there is no point shying away from that," Porter said.
"They were disappointed that the unauthorised or paparazzi, whatever you want to call them, photos were taken. They had tried to keep their kids out of the media ... their faces in particular. They were disappointed that Woman's Day had gone down that path." Porter said the magazine had yet to respond.
The Carters have received lucrative offers from women's magazines to pose with their children, and talk about parenthood. But Porter said: "They would just prefer that their kids were kept out of the media glare. You can imagine that they [the Carters] have had that kind of opportunity plenty of times, and they have chosen not to."
The couple's desire to shield their boys from the limelight is reflected in photos they have released publicly. After Marco's birth in 2013, they posted a black and white photo on social media of his hand in one of his parent's. When Fox was born in April, they released a snap of his feet.
In 2011, the Carters negotiated a deal understood to be worth more than $50,000 with Woman's Day for exclusive rights to their wedding.
"They do have a relationship with these guys," Porter said. "[But] I don't think they have done a women's magazine spread since the wedding."
Woman's Day editor-in-chief Sido Kitchin declined to comment.
Otago University dean of law Chris Gallavin doubted the Carters' privacy had been breached as the photos were taken in a public place.
"They're public entities whether they like it or not," he said. "It's probably a little precious to be honest; that's easy for me to say. They're probably hoping a letter will scare the horses enough for this not to become a common occurrence."
Such photos of celebrities and their children were "bread and butter" in the United Kingdom and the United States but New Zealand had not reached that level. "I think New Zealand media is on the precipice of whether we go into this or not. It will be interesting to see ... how Woman's Day responds."