Carol Friday, 68, and her son Greig Friday, 29, were among the 150 killed when flight 4U9525 came down in the French Alps just over an hour before it was due to land in Dusseldorf.

Ms Friday's niece Georgie Coram, who is visiting the crash site with her father in the coming days, told Fairfax Media the family still held hopes the crash was an accident after the French public prosecutor said investigators were treating it as intentional manslaughter.

"We are holding every hope that is not that way," Ms Coram said.

"It is just too much to bear at this stage to think this could have been intentional."

The Corams are closely tied to the Friday family with Ms Friday's husband Dave Friday asking his wife's brother Mal Coram to travel to the crash site in his place.

Lufthansa airlines, who own Germanwings, have given Mr Coram and two of his daughters open-ended tickets.

Mr Coram and his daughter Georgie flew out on Friday afternoon to meet Mr Coram's other daughter Pippa and her partner in Germany before the four make the journey to the crash site near the Italian border.

"We feel this is an important part of our grief process," Georgie Coram said.

They will carry with them tributes from family and friends in the form of poems, photos and little reminders of the Australian bush Ms Friday and Mr Friday loved to leave near the crash site as a memorial.

Ms Friday, a child and maternal health nurse with the City of Casey, and Mr Friday, a graduate acoustics engineer, were on their way to meet Pippa Coram in Germany, where she lives, when the plane came down.

They were on holidays together before Mr Friday started his two-year stint in Europe where he was going to teach English in France.

"My sister Pippa lost someone far more than a cousin this week," Georgie Coram said.

"She has lost a soulmate, a brother, and a person who has been beside her in one form or another since their births."

The family said Ms Friday was a loving mother-of-two to Greig and his sister Alie, and a devoted wife to Dave. She had three brothers.

Mr Coram said his sister was "one beautiful lady", a talented artist who was his travel partner and great mate. Ms Coram said Ms Friday was the "cornerstone" of the close-knit Coram and Friday clan.

"A deeply passionate and caring woman, who always strove to bring family and friends together, opening up her home and her heart and making people feel welcome" Ms Coram said.

She said her "dear cousin Greigy" was a friend who she imagined growing old with.

"Greig was an engaging, thoughtful, respectful and humble man, a rare and precious being adored by all those who knew him," she said.