MH17 children remembered in Perth

The parents of three children killed on flight MH17 have shared their most treasured possession at a memorial service in Perth.

Mo, Evie and Otis Maslin and their grandfather Nick Norris were returning from a holiday in Amsterdam, where their parents remained, when their plane was shot down over Ukraine.

A short video message from the three children to a long-time friend they were meant to meet during the holiday was screened at a service celebrating their lives on Sunday.

In the video, the three children ride their bikes through a park before telling Aunty Linda they miss her and hope to see her next year.

The children's father Anthony Maslin said while the family had been all over the world, the trip to Amsterdam was the best holiday they ever had.

Mr Maslin said he referred to his children in the present tense because he knew with absolute certainty they were still with them today and that their "unblemished, innocent, perfect souls" were their whole world.

Mother, Rin Norris said her children filled her world with joy like an enormous balloon and taught her so much including all the Dockers players' names, how not to be embarrassing and how to cheat at UNO.

Ms Norris said when the children were born she held them in her arms close to her heart, doing the same when they were hurt to take away the pain.

She said she sang to them in different languages just like "grandfather Nicholas" did to her and had almost finished reading them the whole Harry Potter series.

"When their innocent bodies were shot out of the sky, I stretched my arms as high as I could and screamed for them," Ms Norris said.

"Now I see them only in my head. I can't touch them, I can't feel their warmth.

"My arms will always be reaching for them."

Mr Maslin said it gave the family comfort to know Nick, the wisest man they knew, was with the children when the plane went down.

Nick's son Brack said his dad was a man who put much time into his family with seemingly little effort.

"My dad was a great man," Brack said.

Almost 1000 people attended the service, which was held at Mo and Nick's school Scotch College, including foreign minister Julie Bishop.