In the ongoing wrongful death lawsuit brought against AEG by matriarch Katherine Jackson, Kai Chase revealed that Paris, who is currently recovering in hospital, hasn't celebrated her birthday since her dad passed away.
Describing the 15-year-old as "devastated and lost", she said Paris hasn't had a party since the one Michael threw for her in April 2009 — two months before he died.
"Being daddy's little girl, Paris is devastated. She's devastated and lost," she said. "She's trying to find herself and found out who she is. It's taking a lot of love and understanding to keep her together. She breaks down, she cries, she talks about him."
Earlier in her testimony, she described Paris' last party, held for her 11th birthday, when Michael hired a private circus to perform for his daughter. The Cirque de Soleil-inspired carnival featured men on stilts and a woman performing in a giant balloon.
"Paris hasn't had any birthdays since," Kai said. "She hasn't wanted to celebrate since."
She also revealed that Paris' little brother, Blanket — who was just seven when Michael died — remains home schooled and poignantly said he wears a T-shirt with his father's image on it every Friday.
Michael died in June 2009 following an overdose of a powerful anesthetic, administered by Conrad Murray. The personal physician was convicted of involuntary manslaughter in 2011 and is serving a four-year sentence.
Katherine Jackson is suing AEG for $40bn on behalf of the children, claiming the promoter failed to properly investigate Conrad Murray and missed signs about the singer's health.
Lawyers acting for Paris, Prince Michael, 16, Blanket, 10, and Katherine contend that pressure from AEG led to the singer's death from an overdose of surgical anaesthetic in June 2009, two weeks before his This Is It concerts were to begin at the O2 Arena in London. The company denies any wrongdoing.