Two women, aged 53 and 31, were arrested on arrival at Melbourne airport on Thursday by counter-terrorism officers, the Australian Federal Police said.
Between them, they would be charged with six crimes including keeping and using a slave, and engaging in slave trading, AFP assistant Commissioner Stephen Nutt told reporters in Canberra on Thursday night.
Each offence carries a maximum jail time of 25 years.
A third woman, aged 32, was arrested upon arriving at Sydney airport and is expected to be charged with entering a a declared area and being a member of a terrorist organisation.
Seven children, four women and two men arrived at Sydney and Melbourne on Thursday to face a media storm.
The women and children have spent years in a Syrian refugee camp - it's unclear whether the men who travelled back are children who have grown up or other family members helping the group travel home.
The 14-hour Qatar Airways flight to Melbourne from Doha landed about 5.30pm following a short delay.
A woman, a man and a group of children passed through the international arrivals hall about three hours after their flight landed, with reporters and television cameras waiting.
Other members of the cohort were escorted away by police.
Intermittent scuffles broke out between members of the media and a group of men, some wearing masks, who escorted the new arrivals to a waiting minibus.
Members of the group told media to stop recording, including one man who yelled "turn your f***ing cameras off".
Heavily armed police officers kept the groups apart and barked orders at the crowd as the woman and children were guided into the vehicle.
The "bride" who arrived in Sydney was escorted off the plane by uniformed officers before any other passengers were allowed to leave, people arriving at Sydney Airport told reporters.
She was arrested and taken to Mascot Police Station, an AFP spokesperson said.
While the women face potentially lengthy legal proceedings, uncertainty still surrounds how the children will be integrated into an alien society.
Some women travelled willingly to support their partners who wanted to fight for Islamic State, but advocates for the group say others were coerced or only went to the Middle East to keep their family together.
All children returning home would likely need help integrating into Australian society after years in Syrian camps, while others could need more intensive deradicalisation support, leading extremism researcher Michele Grossman told AAP.
"This is going to be very much case by case," the Deakin University professor said.
"We can't make assumptions that all children will respond equally ... to the kinds of indoctrination activities that we know have gone on in those camps."
The women and children are Australian citizens and government ministers have said there are no practical measures that could have stopped their return.
The premiers of NSW and Victoria said the children returning to their states would undertake deradicalisation programs, and the safety of their communities was paramount.
One woman has been barred from entering Australia on national security grounds and the opposition has reiterated its calls for the entire group to be blocked.
The group forms part of a larger cohort of about 30 women and children who have been trying to return from Syria for years after the 2019 toppling of Islamic State.
