The family of Pheobe Bishop have shared a heartbreaking tribute for her 18th birthday as her accused killers prepare to face court.

Her sister Kaylea Bishop shared a heartbreaking Instagram post on Saturday, uploading a collage of four pictures of herself with her younger sister, including an image of the two in matching white frocks and hair ribbons as small girls.

'Happy heavenly birthday to my angel, the big 18 today,' she wrote in an accompanying caption.

'I miss you so much but I know pop (sic) and you are having an absolute ball up there partying, thrashing cars but most of all leading each other astray and to the next adventure.

'Heaven is lucky to have such a beautiful angel. I'll see you when you're painting the sky beautifully for us tonight. I love and miss you sis.'

Her message comes as Pheobe's housemates Tanika Bromley, 33, and James Wood, 34, prepare to face court over her alleged murder.

At a mention in August at Bundaberg Magistrates' Court, in which the pair did not appear, Bromley's defence lawyer Nick Larter proposed an adjournment to October 27.

Pheobe's family, who were present in court and dressed in black, protested that the date would have been on the girl's 18th birthday, the ABC reported.

Pheobe's sister Kaylea shared an emotional birthday tribute on October 25

Pheobe Bishop went missing on May 15 - her body was found 22 days later

It was then decided the matter of Bromley and Wood, who are each charged with murder and two counts of interfering with a corpse, would instead be mentioned again on November 3.

Brave Kaylea, thought to be in her early 20s, has emerged as a family leader amid the tragedy.

She has physically shielded her mother Kylie Johnson from media questions, and in June spoke bravely at a community memorial for Pheobe in Gin Gin attended by hundreds of mourners and several TV crews.

Pheobe - who was living in the small town west of Bundaberg with Wood and Bromley - went missing on May 15, when she vanished on her way to the local airport.

It is understood she was catching a morning flight to Brisbane, on the first leg of her journey to Perth, to visit her boyfriend Levi.

Police revealed she was last seen in a grey Hyundai ix35, which was also declared a crime scene, along with the Milden Street home she shared with Bromley and Wood.

A huge land and waterway search, involving Queensland Police, SES, cadaver dogs, divers and AirPol, was launched.

Pheobe's housemates were arrested on June 5 and were each charged with one count of murder and two counts of interfering with a corpse.

Brave Kaylea, seen with her mother Kylie Johnson, has emerged as a family spokesperson

Pheobe, in maroon, is seen with Kaylea, (left), Kylie, stepfather Ray and other family

Police found Pheobe's body in the remote Good Night Scrub National Park

The following day, police found the teenager's remains in an isolated, wild dog and pig-infested area of Good Night Scrub National Park.

Bromley and Wood are remanded in custody, with police alleging Pheobe was murdered not long after the car was seen on a home's CCTV near Bundaberg Airport.

Police allege her body was moved twice - first on the day she disappeared, and again on May 17.

In August, Prosecutor Vicki Kennedy-Grills told the court police officers had been working at length to gather a 155-exhibit brief of evidence, including witness statements and CCTV footage.

She said the brief would also include phone and message data, photos, and post-mortem documents.

In July, a third person was charged in relation to Pheobe's death.

Kieren Daniel Mittelheuser, 30, was charged with two counts of accessory after the fact to murder.

It is alleged he used Ms Bishop's mobile phone to interfere with investigations.

James Wood is remanded in custody, co-accused of his housemate Pheobe's murder

Tanika Bromley is also before the courts, and her case will be mentioned on November 3

The teenager had been living with Wood and Bromley at a Milden Street home in Gin Gin

On October 13, he dramatically missed court for a second time.

Just 12 minutes before he was scheduled to appear in Bundaberg Magistrates' Court by video link from the Arthur Gorrie Correctional Centre, where he remains in custody, the court heard he had experienced a medical issue and would be unable to attend.

This came after Mittelheuser was also scheduled to attend court on August 25, but was excused when the video link was cancelled by the centre.

He is also charged with a string of other offences, and is due to appear via video link on December 15.