The family of four children who were killed in a nightmare crash three years ago have honoured their children in a new event.

Antoni, Angelina and Sienna Abdallah and Veronique Sakr were walking to buy ice cream when their lives were taken after a drunk driver veered onto a footpath and killed them in Oatlands, western Sydney, in 2020.

Their mum Leila Abdallah wished to hold an i4Give festival in Prince Alfred Square in Parramatta in memory but the event was delayed because of the Covid pandemic. 

The festival went ahead for the first time on Saturday with Prime Minister Anthony Albanese, NSW premier Dominic Perrottet and ex-prime minister Scott Morrison in attendance. 

'This is the park where I used to come all the time with my children,' Ms Abdallah said.

'Although Antony, Angelina, Sienna and Veronique are not present in body, but believe they me are present in their spirit.'

Ms Abdallah shocked Australia when she forgave the driver who killed her three children and niece just days after their shocking deaths.

Prayers were read for the lost siblings to start the proceedings.

Veronique's father, Bob Sakr was emotional as he said there wasn't 'anything in the world' he wouldn't offer to give his daughter one last hug.

'When I heard Leila say she forgave [the driver], that wasn't going through my head,' Mr Sakr said.

'But then I very quickly I realised I was only burdening myself.'

The i4Give day foundation was set up by the Abdullah family in the wake of their children's deaths, with its mission statement aiming to 'increase community awareness of the power of forgiveness to transform human relationships and to provide resilience toward human flourishing'.

The festival is due to become an annual event filled with amusement rides, live performances, and an outdoor movie showing to cap off the day.

Mr Morrison and his wife Jenny were there in support of the family who they became close with after the tragedy occurred during his term of leadership.

Dressed far more casually than the other politicians in attendance - in blue jeans, sneakers and a baseball cap - he marvelled at the family's ability to forgive unconditionally the person responsible for their children's deaths.

'People ask me often, 'How did they do that?',' Mr Morrison said.

'I couldn't imagine that faced with something like that I could have turned up at that site like Leila did and just say immediately, 'I forgive'.'

Opposition leader Chris Minns was also in attendance at the festival.

Mr Albanese paid tribute to the young children whose lives were 'cruelly snatched' from the world.

'Their bright, beautiful lives, full of promise and possibility, brought to a sudden and a tragic end,' Mr Albanese told the crowd.

'We remember today all the joy and laughter they brought into the lives of those who knew and loved them. The pride. The delight that comes with a child.

'And we embrace in our hearts those still living with the pain and loss. Theirs is a grief that may soften with time, but it will never truly fade.

'Yet in the midst of this sadness, there is something quite beautiful here today as well - and so powerful.'