Fewer than 30 children remain on Nauru as medical transfers of asylum seekers and refugees continue, but many families are still separated even within Australia.

Last week, the Australian government said it intended to bring all children and their families sent to Nauru for immigration detention back to Australia before the end of the year.

The policy flip came amid growing public opposition to offshore processing and mounting internal pressure as increasingly serious medical cases came before the federal court.

On Monday, another 25 people, including eight children in six family units, were brought to Australia by charter flight, leaving 27 children on the island.

A seven-year-old boy, who arrived on Nauru as a three-year-old, was transferred with his family last week.

A young Iranian woman, Mina, has also been flown from Nauru for medical treatment.

Asylum seekers and refugees transferred to Australia for medical treatment often spend weeks in hotels or detention centres before being moved to community detention residences.

Advocacy sources have said it was expected that authorities would take a couple of weeks to source accommodation and schools for people to live in the community, but they are monitoring how long families are remaining in onshore detention.

Guardian Australia understands there areseveral people under Serco supervision at a Brisbane hotel, while others have been sent to detention or hospitals in Sydney, Melbourne, Perth, Adelaide and Brisbane.

Families with underaged children have been sent to a residential section of Melbourne Immigration Transit Accommodation (MITA) – at least 17 children were there at one point last month.

Some are being reunited quite quickly after arrival, including two Syrian boys, aged 12 and 14, who were in hospital for mental health treatment for two weeks, accompanied by their father. They are now in the residential section of MITA with their three older brothers.

However, concerns linger over many of the adults still on the island, as well as numerous families and couples separated between the two countries and even within Australia.

A pregnant Somali woman was in the Villawood detention centre for four months until she was released into community detention this week, while her husband remains on Nauru.

Nauru-based siblings Narges and Daryoush were transferred to Sydney last week after more than four years of being separated from their parents and sister, but remain in Villawood detention centre instead of being put in community detention with their family.

“After more than five years, scrimmaging with illness and pain in a muggy tent on Nauru, it is intolerable to see my debilitated daughter is surrounded by the fences and my children are still separated from me,” the siblings’ mother Nasreen told Guardian Australia.

Two families are facing identical circumstances – the mother is in hospital receiving mental healthcare while the children are in detention, and an Iranian family has been split between Sydney and Melbourne.

A Lebanese mother and daughter who came to Melbourne for medical treatment a month ago are in community detention but another daughter of hers, 14, and her son are in MITA.

Médecins Sans Frontières, which was kicked off Nauru by the government last month, and the UNHCR have said it is not enough to get children off the island, and that all asylum seekers and refugees must be evacuated.

The process of transfers has been complicated by sporadic interference from Nauruan authorities, who have refused to allow transfers or for air ambulances to land, regardless of whether the transfer was ordered by Australia’s federal court.

The Australian Department of Home Affairs has spent at least $780,000 since July last year responding to court applications for urgent medical transfers, and is continuing a legal challenge to the federal court’s jurisdiction to hear the cases.

On Friday the prime minister, Scott Morrison, who was previously immigration minister, defended the Coalition’s policies. Morrison said there was no decision “free of moral burden”, but he did not want border force agents to have to pull dead children from the water if boat crossing attempts increased again.

Morrison said he had prayed for the children in detention on Nauru and he hoped it had made a difference.