Janet Jackson says she will not attend a tribute concert in Cardiff honouring her brother Michael because it coincides with the trial of the doctor charged over the King of Pop's death.
Janet Jackson said the timing of the show would make her appearance too difficult.
She joins brothers Jermaine and Randy Jackson, who also have said they will not attend the October 8 show because it will happen during the trial of Dr Conrad Murray.
The show has received support from family matriarch Katherine Jackson and other siblings of the late singer.
Opening statements are due to begin in Murray's trial on September 27.
Yesterday the judge ruled that the defence cannot call any witnesses to give evidence about the child molestation probe that led to the pop star's trial and acquittal in 2005.
Prosecutor David Walgren argued that lawyers for Murray were seeking to engage in character assassination of the victim in the involuntary manslaughter case.
"The people are concerned about this trial deteriorating into an attack on Michael Jackson," Mr Walgren said.
The hearing took place on what would have been Jackson's 53rd birthday.
Superior Court judge Michael Pastor barred a half-dozen witnesses related to the molestation case, including the detective who headed searches of Jackson's Neverland home in Santa Barbara County in 2003.
The judge said such testimony would be distracting and misleading for the jury in Murray's trial and was irrelevant.
Jackson was acquitted of all charges in the high-profile trial in Santa Maria in 2005.
The judge said he was barring any mention of the molestation case because "it proves nothing regarding the year 2009" when Jackson died.
Defence lawyer Edward Chernoff said he was seeking evidence that in the past Jackson had been addicted to the painkiller Demerol.
Mr Chernoff repeated a previously-stated defence position that the pop star was addicted to that drug and was withdrawing from it when he died of an overdose of the anaesthetic propofol and other medications in June 2009.
Mr Walgren, however, said Jackson's autopsy found no Demerol in his body.
The judge effectively blocked the Demerol defence when he also excluded the testimony of Dr Arnold Klein, a dermatologist blamed by the defence for giving Jackson Demerol. Judge Pastor said written reports on Dr Klein's statements could be used but neither the doctor nor his assistant will testify.
Murray, who has pleaded not guilty to involuntary manslaughter, could face up to four years in prison if convicted.
Authorities say he gave Jackson a lethal dose of propofol and other sedatives in the bedroom of his rented mansion on June 25, 2009.