Now, after a coroner on Friday delivered his findings into their deaths, Caitlyn's grieving father says the onus is on the sport's governing body to implement his safety recommendations and prevent further tragedy.

"There are so many equestrian riders in Australia who are young men and women with parents like us and we don't want any parent to have to go through what we went through," Mark Fischer said.

Deputy state coroner Derek Lee found a jump one of the girls died on may have been safe by Australian standards but exposed riders to higher risk than necessary.

Seventeen-year-old Olivia died after she and her mount Coriolanus tumbled at the barrier at the Scone Horse Trials in March 2016.

It was revealed at the inquest that in the 10 minutes after she fell, officials were calling Dr Philip Janson, who was listed as the event doctor but wasn't even in Scone that day.

Dr Janson's wife, Dr Lyndel Taylor, was supposed to replace him but the change wasn't confirmed with her and she told the inquest she would have declined the position anyway.

Not everyone in authority even knew of the flawed arrangement, with officials proceeding to call for Dr Janson as Olivia lay dying. It was only by chance Dr Taylor heard of the emergency and was rushed to the scene.

During this time Olivia was in the hands of David Keys, a qualified combat medical attendant with the army reserve who was employed through private firm Health Services International in only a first aid capacity.

Mr Lee said he found it troubling Mr Keys' ambulance did not have the necessary equipment to save Olivia even though he had the skills potentially to do so.

Olivia's mother Charlotte Inglis told the inquest she had to watch Mr Keys "struggling" as her daughter lay dying.

She and her husband, Arthur, had no idea Equestrian Australia no longer provided licensed paramedics at events.

Similarly, 19-year-old Caitlyn's mother, Ailsa Carr, was on scene in the aftermath of her daughter's accident.

She was killed instantly when her horse Ralphie landed on her as they somersaulted over a jump at the Sydney International Horse Trials in 2016.

Ms Carr said she knew immediately her daughter was dead but officials didn't and it took at least five minutes for medical help to reach them.

Mr Lee on Friday made 31 recommendations to improve the safety of the sport.

He urged EA to mandate that at every event there is at least one medical response team comprising two providers and, where possible, one one of them be the event doctor.

He also recommended EA change its rules to require medical teams to arrive at serious accidents in three minutes or less, where possible.

Mrs Inglis told the inquest she expressed concerns about a number of jumps at the Scone course before the event, including the one her daughter died on.

Mr Lee provided a detailed analysis of the fence, finding that while it was appropriate, safe and rule compliant, it was not in "entire conformity" with Federation Equestre Internationale guidelines.

Australian Associated Press