WARNING: DISTURBING CONTENT

A couple with part-time care of two young children have been ordered to stop exposing them to sex and their polyamorous lifestyle after concerns were raised about their wellbeing.

One of the children, a girl aged 9, was showing sexualised behaviour when playing with her Barbie dolls, while the other child, a 4-year-old boy, started daytime wetting.

They were part of a blended family and the girl's father and boy's mother say the children have suffered psychological abuse under the care of the polyamorous couple.

A Family Court decision released today revealed the couple, Carl and Judith Blake* led a polyamorous lifestyle, where they had sexual or romantic relationships with two or more people at the same time.

They had sex with others in their open lounge when the children were home and spoke crassly about sex in front of them.

Carl's son Lucas, 4, and Judith's daughter Valerie, 9, became step-siblings when the couple met and fell in love in 2018. Lucas was only 16 months old when Carl moved in with Judith shortly after they met.

She was living with her fiance at the time, so the three adults shared a bed while the toddler slept in a cot in the same bedroom.

Judith's fiance left the relationship several months later, and she married Carl in February 2019.

One evening in October that year, Lucas, Valerie and Judith's two other teenage sons were all at home when a sexual encounter took place with a Tinder date in the lounge.

The house was fairly compact, with Lucas and Valerie sharing a bedroom at the end of a hallway leading to the open-plan lounge. There was no door between the hallway and the lounge. The teenage boys were in a detached sleepout behind the home.

Judith said she did not join in the group sex but watched on the couch to keep an eye on the young children's closed bedroom door.

They said there was no risk of any of the four children walking in on them because Judith would have intervened - a comment Judge La-Verne King dismissed.

"I do not accept Judith's attention was entirely focused on keeping an eye and ear out for the children. She chose to remain in the lounge while Carl and [the other woman] were engaged in sexual activity," Judge King said in his decision.

A more child-focused approach in that situation, the judge said, would have been for the adults to have sex in a part of the house that was out of earshot and eyesight of any of the four children at home that evening.

Interviews also showed the two teenage boys were aware the couple had sex in the lounge when they had friends over.

"So now; if I go inside, I put my headphones on so I can't hear anything and I don't look. I know where the toilet is so I curve around so I don't see anything," one of them told the court psychologist.

The couple had agreed with Valerie's father not to introduce her to any new partners, with the only exception allowing friends over in a platonic setting like a board game night.

But Judith and Carl took this to mean board game evenings could end in consensual sex between the adults while the children were in their care.

This showed the polyamorous couple's lack of insight into the need to mitigate any harm to Valerie and Lucas, Judge King said.

The court psychologist who interviewed Valerie said the little girl knew what the word orgy meant at the age of 8. Her father also raised concerns about her sexualised behaviour and language.

A family friend whose daughter Molly was on a playdate with Valerie overheard the two girls speaking in hushed voices while playing with dolls in the bedroom.

She slowed down, and through a crack in the door, heard Valerie say the words "orgy", "p***y", "c**t", and "c***k", and Molly, two years younger, repeated after her.

Shocked and horrified, she entered the room and saw the two girls holding a naked Barbie doll mounted on top of a Ken doll, then quickly dropping them in embarrassment.

A month after the incident, Molly came home after a play with Valerie and told her mother that the older girl was "making the male doll be angry and violent with two girl dolls for being 'cheating sluts'".

Witnesses described the couple as making no attempt to curb their language when the children were around, and Carl would speak openly at dinner about going home to have "loud sex" with his wife, according to Valerie's stepmother.

Lucas started daytime wetting both at home and at daycare after Carl's contact with him was no longer supervised, his mother said.

The 4-year-old was also showing distress, aggression and throwing "major tantrums". "Carl can't put his sexual needs behind Lucas' needs," the toddler's mother said.

Valerie's father and Lucas' mother said their children have suffered psychological abuse under Judith and Carl's care because the polyamorous couple has prioritised their own needs over the children's.

But the polyamorous couple maintained each child was safe with them.

Judge King ruled against Carl and Judith, issuing a final parenting order that they stop exposing and educating Lucas and Valerie in their polyamorous lifestyle.

This means they must have no direct or indirect exposure to sexual language or activity, and not be introduced to any sexual partners.

The judge also found an "unacceptable risk" to Lucas's safety while under his polyamorous father's care, and ordered the two only have unsupervised contact in the daytime.

* Names have been changed to protect the identities of everyone involved in the case.