Luke Davies' brother's emotional farewell to the flight attendant allegedly murdered alongside his partner Jesse Baird

Family and friends are arriving at the funeral of Qantas flight attendant Luke Davies after was allegedly murdered alongside partner Jesse Baird by a NSW Police officer, with his brother John telling the assembled his sibling was taken 'too soon'.

Police allege Constable Beau Lamarre-Condon killed Mr Davies, 29, and Mr Baird, 26, at the latter's terrace house in Paddington in Sydney's east on February 19.

A memorial service for Mr Davies is due to begin in a matter of minutes at local park in the Brisbane suburb of New Farm, where Mr Davies previously had resided.

Hundreds of loved ones are flocking to the park, many wearing white in honour of Mr Davies.

Two large screens outside the park's rotunda are showcasing photos of Mr Davies, along with a floral tribute of sunflowers.

'I will go on forever trying to forever be like you… you were taken from us far too soon,' his brother John said. 

Claire Horsfield, a close friend of Mr Davies who met him through mutual friends, said today marked a celebration of his life.

She said she was surprised at the sheer number of people attending.

'It shows the impact he had: he was just one person but everyone has been brought here today,' Ms Horsfield said.

'It's a sad moment but it's one we want to cherish.'

A reception is expected to be held at the nearby at the nearby Powerhouse Museum after the memorial, which comes after widespread grief over the couple's death.

National airline Qantas paid tribute to Mr Davies at Sydney's Mardi Gras parade in March, with the nose cone of a plane bearing his name featured in their float.

A GoFundMe page run on behalf of Mr Davies' mother, Sandra Davies, raised more than $75,000 since the couple's alleged murder more than two months prior.

In an update in March, Ms Davies thanked all those who donated - some as much as $2000 - to her 'beloved, and most beautiful, kindest son Luke'.

'These words just don't seem enough for the overwhelming love and generosity both Luke and Jesse have received these past few weeks,' she said.

'To all the family, friends, and strangers for your generous gifts and words of support we appreciate all of your help during this very traumatic and difficult time.'

According to the campaign, the funds are to be used to 'help his (Mr Davies') family in this tragic time and help give him the send off he deserves'.

Partner Jesse Baird, who was a producer with Network 10, was earlier farewelled by family, friends, and colleagues at a funeral in Melbourne in March.

The bodies of Mr Davies and Mr Baird were found at a remote property in Bungonia, some 200km southwest of Sydney, on February 27 - just shy of a week after they were first reported missing.

Beau Lamarre-Condon, a former NSW Police constable, has been charged with the couple's murder - allegedly using his police-issued firearm - at Mr Baird's inner-city Paddington home on February 19.

He is alleged to have dumped the pair's bodies at the Bungonia property on February 22.

The couple's deaths sent shockwaves through Sydney and led to an outpouring of grief across the nation.

Several vigils have already been held for the couple - including a silent gathering of 60 people in Bronte to honour Mr Davies' life.

Last month, hundreds of mourners donned brightly-coloured clothing to farewell Mr Baird at a memorial service at the Plenty Ranges Art and Convention Centre, north of Melbourne.

Mr Baird's mother Helen said there was 'less sparkle in the world' in a heartbreaking speech about her loss.

'My beautiful, generous, loving, precious, caring and talented boy, our hearts and lives are changed forever,' she said.

'I promise to fight for you and make you proud. My heart is broken, my darling boy, and I love you more than this world.'