"She was a special girl," her devastated father Ian said this week, speaking publicly for the first time about the death of his beloved daughter.

Riharna died at Canberra Hospital on March 3 after falling from her favourite horse during trackwork on February 28 at Thoroughbred Park ahead of the national capital's premier race day, the Black Opal Stakes.

The 22-year-old donated her kidneys, pancreas, liver, lungs and a heart valve, the organs thought to have helped six to eight people.

One recipient, whom the family believes was a young man, received a kidney. He wrote an emotional handwritten letter to the Thomsons thanking Riharna for giving him a second chance.

"We're assuming he's male, we don't know," her mother Carolyn said. "He didn't sound very old. He was about to get married."

Mr Thomson said the person who received Riharna's kidney had also been "outdoorsy", just as she was.

"He made a comment in his letter that as soon they connected everything, everything went straight to work and he was progressing better than they expected him too," he said.

Riharna, known for being a thoughtful and determined girl, had registered as an organ donor before her death.

"I can still remember the afternoon we were just sitting out the back and she brought it up that she was going to do it and I was like, ' Oh, yeah, it's never going to happen to you' sort of thing," Mr Thomson said.

And then the unthinkable happened. Their brave, independent daughter, the "kid you didn't have to worry about", had suffered serious head injuries in the fall from the horse and was on life support.

Her parents were candid in explaining how confronting it had been in the hospital dealing with the organ donation as they were still coping with the sudden death of their daughter. Mr Thomson's first instinct was to protect his little girl, even though she was gone.

"After the time came when we knew she wasn't going to recover, a representative from Donate for Life came around and said, 'Did you realise?' and I was like, 'Oh, yep, here we go'," he said.

"And it was real sort of, 'There's no way in the world you're going to come in and attack her body and just take what you want'. But then sitting down and realising and them telling us, 'You could probably help six to eight people in doing it'.

"And since we've done it, it's probably one of the major things that has helped us get over it, Knowing that there's people out there that have received the organs."

The couple, who had businesses in Tamworth and Walcha and now run a hotel at Salamander Bay near Newcastle, have chosen to speak about their daughter's last gift during DonateLife Week from July 30 to August 6.

The week is about urging Australians to join the Australian Organ Donor Register at donatelife.gov.au and discuss their donation decisions with their loved ones.

The Thomsons feel some peace despite the situation being daunting at the time.

"As awful as the decision was, at the end of the day it felt right," Mrs Thomson said.

"And it is, it is the right thing to do. All those misgivings sort of left us when we made the decision."

Mr Thomson agreed.

"It's like she's still out there. Not Riharna, but she's helped someone else sort of thing," he said.

When Riharna's organs were being transported out of the hospital to be taken to the Canberra airport for flights to interstate hospitals, her family, friends and workmates formed an impromptu guard of honour in the carpark as they were taken away.

The Canberra - and national - racing communities were rocked by her death.

Jockeys, strappers, trainers and owners were united in their grief.

Leading jockey Tommy Berry attended Riharna's funeral in Tamworth and dedicated a win at Royal Randwick to her.

The Canberra Racing Club will name a race in her honour at the Black Opal Stakes, the next on March 11. It will be named the Riharna Thomson Bracelet, with the trophy, a bracelet, to go the winning jockey.

"We had no idea how well-regarded or how well-known she was. It sort of gobsmacked me with the amount of people who knew her," Mr Thomson said.

The Thomsons said Riharna was about seven when she got her first horse, riding it on their property at Tamworth. She went to the New England Girls' School in Armidale which had an equine complex and encouraged her love of horses.

Mr Thomson said he did worry about his daughter riding race horses but she always just smiled and told him it was all okay.

"It was always in the back of your head but it was never going to happen to her," he said.

Riharna was studying politics at the Australian National University in Canberra, something which "came out of left-field" as the family was "not political at all".

"I think realistically, as much as she liked politics, I think horses is where she was going to go in the end," Mrs Thomson said.

"That was going to be her life focus."

The Thomsons have two boys, Colin; 21; and Braden, 20; and their daughter Bessie, seven. They see a lot of Riharna in Bessie, who also loves horses.

They think of Riharna "every day". Quiet. Determined. Able to talk to anyone.

"She knew what she wanted out of life and it didn't matter what obstacles were in her way," Mrs Thomson said.

"She was going to do it. And she wanted to do it on her own."

Her brothers and friends used the hashtag #rideonriharna in social media posts following her death. It now has even more meaning as her gift of life, her organ donation, created the greatest legacy for a young girl who just loved horses.

* For more information about organ donation go to donatelife.gov.au

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