Experts and victim advocates have shared their concerns with the Morrison government's move to fold the Family Court into the Federal Circuit Court.
A Bill combining the courts received the federal Parliament's final approval on Thursday after passing through the Senate.
The Morrison government insists the change will reduce backlogs with as many as 8000 extra cases resolved each year.
In a joint statement, however, the Law Council of Australia, Women's Legal Services of Australia, the National Aboriginal and Torres Strait Islander Legal Services, and Community Legal Services Australia described the merger as a "disappointing outcome for Australian children and families".
"There is much more evidence to support the damage that will be done by the merger, including harm to families and people experiencing family violence," the statement read.
"The government and new court will be under heavy scrutiny to deliver court efficiency, resolve 8000 additional cases, reduce costs, reduce the time separating families will spend before the court and reduce delays, even allowing for the impact of Covid-19.
"Like many others, we have warned of the dangers this legislation poses for the most vulnerable in our community at a time of relationship breakdown.
"We now call on the government to step up and properly fund the family law system and legal assistance, and to repair the years of government neglect of this critical infrastructure."
Women's Safety NSW chief execute Hayley Foster said the merger decision seemed premature, given parliamentary inquiries into both family law and domestic and family violence have just been complete, with recommendations yet to be handed down, and recommendations from the Australian Family Law Reform Commission have also not been implemented yet.
She said the merger was a difficult situation.
"Our members, who are the Women's Domestic Violence Court Advocacy Services supporting more than 50,000 women experiencing domestic violence each year, are somewhat split over the decision," Ms Foster said.
"In metropolitan areas, where families have access to the current Family Law Court of Australia, there is concern that the merger will result in less specialisation of the court, particularly in high stakes cases involving allegations of family violence and abuse.
"In regional, rural and remote areas, there is more support for the merger on the basis that there is a current lack of access to specialist family law judges and support services in these areas, and the merger might change this.
"It certainly is the case that it makes no sense to have two parallel pathways for family law disputes to be judicially determined.
"Our concern is that specialisation of family law judges and court staff continue to be further developed."
Ms Foster said if that specialisation was reduced or lost it would be damaging for victims seeking justice.
However, she noted the "current state of play in the family law system is not ideal".
"Victim-survivors with cihldren have told us that the family law system as it currently stands is the single biggest barrier to them achieving safety," she said.
"While there are some brilliant family law judges, overall, there remains a very strong focus on maintaining contact with both parents, notwithstanding the risk of violence and abuse to children and their primary carer.
"We have countless cases of women choosing to stay in a violence and abusive relationship purely to protect their child from having to have unsupervised time with their abusive parent - and that's intolerable."
Ms Foster said she would be interested to see how the standards of family law judges will be enforced with the merger: "judges should be required to demonstrate a strong understanding of the dynamics, patterns and impacts of family violence, including coercive control, and this should be reflected in their previous handling of matters".