On arriving at the victims' Napier house about 9am, Jury accused the woman of lying to the Mongrel Mob, then hit her head, knocking it against a door.
Jury went into a bedroom where the woman's partner had been sleeping and began beating him while he lay in bed. He punched him several times to the right side of his face, and kicked him twice in the head.
Jury was brandishing a hammer and yelling at the man, "You are lying to the Mob", and "You guys owe the Mob", according to the Crown summary of facts.
While Jury was assaulting the man, Lay and the other woman started taking things from the house, including a 55-inch television, a gaming console, a watch, cigarettes, cash and bank cards, an ornamental sword, a cellphone, keys to the house and vehicles, and a scanner capable of listening to the police radio frequency.
When spoken to by police later, Lay told them that she had known the female victim all her life. She was Lay's cousin.
Judge Matenga said he had received reports which detailed what he called "a sad and disturbing story".
"In my view there are numerous and serious causative factors outlined which help me to understand your offending," Judge Matenga said.
He said Lay had been taken into state care as a child and had been in care for a long and unsettled time.
She had been exposed to child abuse, sexual abuse, substance abuse, gang associations and "severe family dysfunction".
Added to that were her own medical diagnoses of fetal alcohol syndrome, attention deficit hyperactivity disorder, attachment disorder and anxiety.
Another judge had given a sentencing indication with a starting point of five years.
After considering the reports and taking into account Lay's guilty plea, a "genuine" letter of remorse, her age, and her willingness to undergo rehabilitative treatment, Judge Matenga jailed her for 30 months.
Jury has been dealt with separately by the courts.
In November last year he was sentenced to five years and two months in prison for aggravated robbery and other charges, including family violence and resisting police.