New Aussie comedy-drama about 1970s family life Swinging Safari is full of cringe-worthy moments. But for two of its stars, filming on set could have involved just as many.

That’s because Kylie Minogue and Julian McMahon – who play halves of three bored couples who decide one night to swap partners – used to know each other very well. In fact, they were family. Were being the keyword.

For those who weren’t alive or don’t remember Kylie’s younger sister Danni Minogue and McMahon were married for 18 months during 1994 and 1995.

Making matters worse, it didn't end on the most amicable of terms either. In an interview in 2010, Minogue said the decision to separate was strongly influenced by her ex-husband's mother, Lady Sonia McMahon.

"I was never accepted. It was never made clear to me why things were taken out on me. In my mind, I'd done nothing against her. But simply being with Julian was, in her mind, the wrong thing to do," she told Britain's Glamour magazine.

"It shaped me... it definitely wasn't easy for anyone - not for her, not for Julian, not for me. Nobody was having fun.

"Things really did come to a head. There was an unease that had been going on for a long time, but I caused some kind of explosion."

At the time, Minogue said she was certain she and McMahon were "never going to be friends".

Thankfully, things don't seem to be the same for her older sister, who plays not entirely interested parent Kaye Hall, to Guy Pearce's Keith Hall.

Asked about the potential awkwardness by Herald Sun's Neala Johnson, McMahon said more than two decades on it was all water under the bridge.

"Oh look, I never had any weirdness to be honest," he said. "First, it feels like another lifetime ago, so it’s hard to relate to it completely.

“But Dannii and I loved each other — the relationship didn’t work but we had an incredible relationship when we had it. And Kylie was an amazing sister-in-law. She sung at our wedding and that was pretty fricking special."

"The sad thing is that it didn’t last ... it’s just what happened, you know".

While acknowledging breakups will always make things "a little bit weird", McMahon said it wasn't on his mind while filming Swinging Safari.

Still, we're going to be watching the scene where they apparently kiss very intently.

You can catch Swinging Safari in cinemas from Thursday, 18 January.