New mum Abbey Forrest, 19, and her partner Inda Sohal, 28, died in the blaze alongside their daughter Ivy, who was just 19 days old.

Jenny Hayes, 46, was charged on Thursday evening with three counts of murder and three of arson causing death.

It's alleged she deliberately set fire to the Point Cook townhouse on Wednesday morning. The young family had only moved in three weeks earlier.

Hayes was due to face Melbourne Magistrates Court on Thursday evening, but her lawyer Erin Byrt said her client, who was still at the Richmond police station, had asked to proceed in her absence.

Magistrate Luisa Bazzani questioned what the relationship was between Hayes and the family, but Ms Byrt said that had not yet been disclosed.

She also declined to elaborate when the magistrate said she had been told Hayes' state in prison was poor.

"That about sums it up at the moment," Ms Byrt said.

The court heard Hayes takes medication for restless leg syndrome and arthritis and she will undergo a medical assessment. It is her first time in custody.

Hayes is due back in court on March 1.

Australian Associated Press