Two 15-year-olds are to go on trial accused of murdering a mother and daughter.
The accomplice denied murder but admitted a charge of manslaughter.
The 15-year-old girl, who can not be named for legal reasons, admits manslaughter but denies murder.
Among them were Ms Edwards' older daughter, Mary Cottingham, her partner Graham Green, and her ex - Katie's father - Peter Edwards.
They had both been stabbed in the throat.
"The mother was killed first while Katie slept".
He stabbed Liz Edwards in the throat as he pinned her down while kneeling astride her.
The jury heard the boy carried out the murders but the girl's defence to murder is that her responsibility for the killings was diminished by her mental state.
The court heard they made a decision to stab both victims in the throat so that no noises would be heard from them.
"It seems probable that Katie was also smothered with a pillow and from the position of her body may have tried to move away from her attacker".
Jurors were told the girl listened to them "struggling and gurgling" as they were murdered in the semi-detached property.
He told the court how they then enjoyed watching several episodes of Twilight together before they were arrested 36 hours later.
In police interviews the girl said the plot was hatched four days earlier and further discussed in a McDonald's.
Ms Edwards had also been stabbed once in the shoulder, and twice - fatally - in the neck with one blow which "almost completely cut through her windpipe".
Sgt Christopher Fletcher, from Lincolnshire Police, told jurors of the moment he discovered the teen's body under a sheet. I touched her to check for signs of life. I was pulling her and shouting, 'Wake up'.
He said: "The sheet came off and I could see a bare torso of a young person. I touched her. She was cold and rigid". The boy has pleaded guilty to the double murder at Nottingham Crown Court.
Joyce said: "The prosecution case is that the girl is as guilty of murder as the boy".
Her daughter was found lying on a mattress in her bedroom under some bedding, with two stab wounds to her neck which suggested "the use of severe force", according to Mr Joyce.
"They were serious in their intention", said Mr Joyce.
"She wanted them to happen".