A 46-year-old woman has been charged with murder and arson causing death over a fatal house fire in Point Cook

A Victoria Police spokesperson said the woman was arrested on Thursday morning in Airport West.

She has been charged with three counts each of murder and arson causing death.

The woman arrested is believed to be an acquaintance of someone who had been staying at the Point Cook property.

She had allegedly visited in the period before the blaze erupted.

Police are not looking for anyone else in relation to the blaze.

Abbey's father Alan Forrest said there were "many unanswered questions" about the circumstances of the deadly blaze.

He said he would not comment on suspicions or allegations of who may be responsible.

"As far as I'm concerned that's for the police to handle," he said.

Mr Forrest spent Thursday on the phone to Indi's relatives in India about potential funeral arrangements.

He said the grief of both families was indescribable.

"It's a very sad situation. Words can't explain it. There are so many unanswered questions," he said.

"It's a very, very heartbreaking situation, which I hope no one ever has to go through."

He said he had only met his granddaughter Ivy twice and was due to have a family dinner with the three of them this weekend.

Abbey, 19, and Indi, 28, were a "beautiful young couple", he said.

"They were naturally loving and caring parents. They always wanted to be together with their precious young daughter who they love very much."

TRIBUTE TO YOUNG FAMILY KILLED IN FIRE

Abbey Forrest and partner Indi Sohal, sadly lost their lives in the suspicious blaze, which erupted at their Point Cook home on Wednesday.

Their almost 3-week-old daughter, Ivy, was also killed, in circumstances the family have described as beyond "tragic."

The couple had only recently moved to the Totem Way property and were enjoying finding their feet as parents.

Her sister, Emily Forrest paid tribute to the young family on Thursday and said their lives had been "cut short."

Ms Forrest said the couple, who had been together for about a year, had their "whole lives ahead of them."

"Abbey deserved so much more than this," she said.

"Life was just getting perfect for her. She was so proud to be a mum, she took to motherhood like a duck to water and Indi adored his daughter.

"It was a new-found love."

She said she would cherish memories from their childhood in Geelong, including horse riding together, attending pony club and athletics.

"We were really close growing up. We rode ponies and did pony club together … and when I moved out of home she would come and stay at my house in Flemington.

"My sister had a big bold personality, she was quirky and she was just great."

The family were on Thursday trying to come to terms with their devastation, with Ms Forrest saying her parents where "beside themselves" with grief.

Ms Forrest and her partner Joel attended the scene to lay a bouquet and leave a teddy bear for their niece.

Their own son, aged 3, is Abbey's godson.

She said she would be "forever grateful" to the hero neighbours and emergency services who tried to save her sister.

"Being able to say thank you to them was really big for me because they were there when I couldn't be," Ms Forrest said.

She said she was lost for words knowing the fire was being treated as suspicious and was potentially deliberately lit.

"They were just a young couple with a young baby," Ms Forrest said.

"I just really hope we get answers."

Tributes for the beloved trio flooded social media on Thursday morning.

One woman described their deaths as an "awful tragedy."

Another promised to "look after your sister for you."

A GoFundMe has been set up to support the family.

Originally published as Woman charged with murder over Point Cook house fire