The woman, who cannot be named, was on Friday sentenced to a maximum of four years’ prison, with a minimum of two years.
However, she has already served 453 days in jail for breaching bail conditions, according to The Age.
The Victorian County Court was told that after the woman’s marriage broke up she moved in to her nephew’s home in 2011 and they started a relationship.
Soon after, while the pair were having sex, the nephew started touching the daughter. The daughter was raped for the first time shortly after.
Horrific details of the abuse emerged early this month, including that the mother held her daughter’s leg so she could get a better view, while the girl cried and told her cousin to stop.
The nephew, who pleaded guilty to persistent sexual abuse of a child aged under 16, was sentenced to nine years in prison.
Judge Clare Quin told the pair “You have taken away her childhood and innocence, and the joys that most children experience”.
She accepted that the woman’s mental health problems and “dependent personality style” were factors. However, there were concerns that the nephew had a moderate risk of reoffending.
The girl, who is now 17, suffers nightmares and has trouble eating and socialising.