News of the legal offensive emerged as the Jackson family met activist Reverend Al Sharpton to disuss plans for a memorial to Jackson.
The star's father, Joe Jackson, told reporters however that no funeral date would be set until results of a second autopsy out on his son were complete.
"We're not ready for that yet because we're trying to wait on something else. We're searching to see what happened to Michael," the 79-year-old patriarch told reporters at a press conference outside the family home.
"We don't have the time frame yet because I want to see how this autopsy's coming out, you know? The second autopsy."
Joe Jackson applauded the court decision to make his wife Katherine the temporary guardian of their grandchildren, Prince Michael, 12, Paris, 11, and Prince Michael II, 7.
"This is where they belong," Jackson said. "We're going to take care of them and give them the education they're supposed to have."
Reports have said Jackson's family is considering a series of simultaneous memorial services around the world for the singer, reflecting the huge global reach of an artist who sold more than 750 million records.
"It is the determination of the family to be careful and deliberate on how they plan his celebration of life, because we're talking about a historic figure that really changed pop culture around the world," Sharpton said.
"This is not something you do carelessly and spontaneously. We must remember they are still grieving and in their grief, determined to uphold his legacy."
Family members attended an awards show Sunday dedicated to African-American entertainers which became a star-studded celebration of Jackson's life, featuring an emotional tribute from his sister Janet.
"My entire family wanted to be here tonight, but it was just too painful so they elected me to speak with all of you," Janet Jackson said.
"I'd just like to say that, to you, Michael is an icon. To us, Michael is family and he will forever live in all of our hearts."
The Jackson family already has hired a private pathologist who has carried out a second autopsy on the family.
Details from Friday's preliminary examination of Jackson's body were published in Britain's The Sun newspaper on Monday after the daily said it had seen a copy of the autopsy report.
According to the paper, pathologists found Jackson's stomach empty apart from partially-dissolved pills. Jackson's body was also reported to have weighed only 50.8 kilograms (112 pounds) at the time of his death.
However the Los Angeles County coroner's office strongly rejected the report, describing parts of it as "totally false."
"The report that is being published did not come from our office," said Assistant Chief Ed Winter. "I don't know where that information came from, or who that information came from."
Meanwhile lawyers for personal physician Conrad Murray -- who was with Jackson in the hours before his death -- went on the attack, with attorney Edward Chernoff insisting his client was blameless.
"There's nothing in his history, nothing that Dr Murray knew, that would lead him to believe he would go into sudden cardiac arrest or respiratory failure," Chernoff told CNN Monday.
"There was no red flag available to Dr Murray, which led him to believe he would have died the way he did. It's still a mystery how he died."
Speculation has been rife that excessive use of powerful prescription pain killers may have played a role in Jackson's death, but Chernoff insisted that contrary to news reports, Murray "never prescribed nor administered" two particular drugs -- Demerol or Oxycontin -- to Jackson.
He also defended how Murray responded to the immediate crisis after Jackson lost consciousness last week, recounting step-by-step the failed effort by the doctor to revive the singer.