Emergency responders found the body of 19-year-old Wangaratta man Charlie Gander after extinguishing a car fire at Bunbartha about 10am.
Kylie Stott, 37, and Danny Clark, 38, faced Shepparton Magistrates Court on Tuesday morning, charged with the teen's murder.
Dimitri D'Elio, 24, faced court on a single charge of murder on Tuesday afternoon.
During separate hearings it was revealed it will take up to four months for an autopsy report to be completed by pathologists because of the condition of the teen's remains.
All three co-accused have been interviewed by police.
It's alleged they murdered Gander within the City of Greater Shepparton on December 24.
Stott's version of events was not consistent with what has been investigated, Detective Senior Constable Alex Nucci told the court.
One of the male co-accused provided a no comment interview while the other denied the allegations, Det Nucci said without going into further detail.
Magistrate David Faram questioned whether others might be charged in connection with the teen's death.
Det Nucci said it was unfortunately a complex case and investigations were still ongoing, noting further inquiries had been made.
He also said potentially hundreds of hours of CCTV footage might form part of the investigation.
Stott's lawyer said the time delay would be prejudicial to her client, who is in custody for the first time.
The Mooroopna woman suffers from post-traumatic stress disorder, anxiety, separation anxiety from her children and chronic back pain as a result of being hit by a car some years ago.
She is also withdrawing from cannabis and methamphetamine, her lawyer said.
Clark, from Shepparton, also suffers anxiety, depression and back pain, and may also suffer mild substance withdrawals, his lawyer Natasha Van Der Heyden said.
D'Elio, also from Mooroopna, was supported in court by his parents.
His lawyer asked that he see a prison medical officer about his diagnosed depression.
All three are due back in court on June 27.