The bodies were found by her 20-year-old son on Friday.
The father said yesterday his daughter had been staying with Warria, her aunt, for about a week.
He last saw his daughter the night before she died at a local restaurant where she was eating dinner with friends. "I said, 'Come with me', but she said, 'Oh no dad, I'm going with my friends, my aunty'," he told AAP.
His daughter had spent many weekends and holidays at the house and there had never been problems.
He said Warria had recently decided to turn her life around and was again attending church.
Queensland Detective Inspector Bruno Asnicar said police were examining several knives that may have been used to kill the children.
He said last night police had spoken to the children's five fathers.
Police are yet to release a cause of death with post-mortem examinations still being conducted.
"Charges are being considered, of course," Asnicar said. "Investigations are continuing, obviously, in that direction." He would not comment on how the woman sustained her injuries, whether she had undergone a mental health assessment, or any other treatment she had been given. He said the Murray St house would remain a crime scene for several days, and police were piecing together exactly what had happened.
The house hadn't "been flagged in any special way" before, but he would not comment if the family was known to child protection authorities. "There [haven't] been particular issues. This is just a devastating thing that's happened; that nobody predicted."
Pastor Michael Gela, who hails from same place as the family, Erub Island in the Torres Strait, is her traditionally adopted brother.
"The family had concerns that she was suffering depression but would not get help. She said to me and my wife, 'I'm not a girl who'll get advice from anyone'," he told the Sydney Morning Herald.
Hundreds turned out for a vigil at a nearby church on Friday night.
City Church Pastor Michael Dalla Vecchia said his message was for people to come together and support one another.
"Love conquers all," he said as residents began streaming into the service, many with their arms around one another.
"Everybody is devastated in this situation, it's hard to speak about. Cairns is such a tight-knit community, when one person feels pain we all feel pain.
"There will be a time of mourning but we will rebuild."
A heavily pregnant mother who lives across the road from the Warria house said she was still trying to figure how she would explain it to her small children.
"Does this happen on every street, Mum?" one asked, pointing towards the crime scene.
