At about five years old, Ellis* realised her father "just wasn't there" — he married another woman and set up his new family in a separate household.
"It was the same for my siblings and I'm sure it was the same for my half-siblings," she told ABC Radio Australia's Sistas Let's Talk program.
"It was just a painful way to be as a child."
Ellis' father was a polygamist, but not in the traditional sense.
"My family's situation was not like… where a man owns a lot of land and requires extra wives to work the land and raise pigs to give him status in society," she said.
"I'm going to put it very bluntly. Polygamy just provides extra sex. I mean, he already had a wife and children.
Polygamy, where a man is married to more than one woman, has a long history in parts of the south-west Pacific country.
Before missionaries arrived in the mid-1800s, wealthy landowners married multiple women to work the land, raise pigs and bear children, which in turn boosted their social status.
But its continued practice today has come under fire from survivors, human rights advocates and organisations.
The UN's Division for the Advancement of Women described polygamy as a destructive and harmful practice that often leads to violence against women and girls, both by husbands and co-wives.
Advocates believe it also gives rise to human trafficking, where women and girls are forced or coerced into marriages.
Despite the PNG government moving to ban polygamous marriage in 2014, the practice persists today.
Being the daughter of a polygamist
Ellis said her mother "refused to tolerate" her father's polygamy, which resulted in him having 10 more children.
Eventually, he struggled to generate enough income to sustain both households and stopped supporting her family.
"[My mother] provided accommodation and food and other needs for us," she said.
"As we got older, it meant we had less food on the table, less [money for] school fees or they were not paid on time and we couldn't pursue higher education.
"We had to enter the workforce early at 16, 17, 18 years old."
She said the "unseen and unspoken" impacts of her father's polygamy manifested years later.
"There were more issues within ourselves that surfaced like depression," she said.
'Pain in my heart'
Depressed and in despair over her husband's marriages, Ellis said her mother self-medicated with valium.
"She told us as we were growing up, 'I took valium because I had so much pain in my heart. I couldn't sleep,'" she said.
"This is real."
Ellis wants men to be held to account for the harm they cause women and children through the practice.
"[Men] put food on the table. They provide the school fees and whatever else and women and children are meant to just shut their mouth and accept this," she said.
"The women just tolerate it or they fight amongst themselves and the children have resentment amongst themselves and it goes on for a lifetime.
Escalating violence, children displaced
In 2014, the PNG government repealed the Civil Registration Act to make it compulsory for all marriages, including customary ones, to be registered.
The move was designed to stop men from marrying multiple women, particularly from different provinces.
But Sarah Garap, a human rights and social justice advocate in Jiwaka Province, said the ban was never properly enforced which has had wide-reaching consequences.
"There's more killing happening, co-wives killing each other and even the men are being murdered by women who suspect they are having adulterous relationships," she said.
Ms Garap founded women's rights organisations Kup Women for Peace and Meri Kirap Suppotim and has three decades' experience working in politics, academia and grassroots activism.
"There's not much educational awareness … there isn't anyone going out strongly advocating against polygamy," she said.
"Children are not in school and not being properly provided for and women are fighting each other.
Ms Garap said children born from polygamous marriages, who are raised outside a village setting, are left behind after a father dies.
"If one child is in Lae, one is in Goroka and one is in Simbu, later on when the father dies, these children… would be seen as displaced; children with no heritage," she said.
Kidnapping, human trafficking in public
Kidnapping and human trafficking are known consequences of polygamy in PNG.
In recent years, Ms Garap said several kidnappings have been attempted by groups of men on the streets of Port Moresby.
"The guys pretend they knew the women in town. They ask, 'Where did you go? You were supposed to return three or four days ago. Why didn't you come back?'" she said.
She believes the situation is "just becoming worse" as girls as young as 15 enter into polygamous marriages, sometimes due to economic hardship.
"Men lure these women into becoming their third, fourth or even fifth, sixth and seventh wife, which is a sad thing," she said.
Escaping a polygamous marriage
Judy Gelua married her husband in the Catholic Church and they had three children. But 12 years later, he decided to take a second wife.
She believes the "big-man chief culture" in the highlands region of PNG normalises the practice.
"They think having so many wives increases their wealth or their fame, or because the woman will produce plenty of children, then the male children are regarded as security for the men," she said.
Despite the initial shock, the single mother-of-three is determined to break the cycle of polygamy while being a positive role model.
"Every time I'm talking to them about polygamy, [I tell them] it's not good and they [should] just have a single partner so they progress in terms of economic and social development," she said.
"All my three children have reached university, so they're very good.
*Ellis' name has been changed to protect her identity.
The national family and sexual violence helpline for callers within Papua New Guinea is 715-08000.
