Baby Phoebe was born with two life-threatening conditions

** Due to the continuing pandemic this event has been moved to April 3.

Molly didn't even get to meet her sister Phoebe before she died but she always tells everyone she has two sisters.

Molly, 10, and Lucy, 13, have always known about Phoebe thanks to their parents Angela, 39, and Chris, 41.

Despite having lost her so young, Phoebe lives on in their hearts and minds and through Molly's incredible work to raise funds for the cruel disease that claimed her life so young at just seven months.

Phoebe was born five-and-a-half weeks early.

RELATED: YouTube star put in induced coma day after giving birth amid coronavirus battle

"My waters broke at home," Angela tells 9Honey. "She was in neonatal care for four weeks and we went home and a couple of weeks after a midwife came to check on her and told us something wasn't right and we should take her to hospital."

At the time Lucy was only two and Angela hadn't noticed anything was wrong with her little girl.

"They found that during labour she'd has a brain haemorrhage," Angela says. "A couple of days later she had an operation. They put a shunt in to drain the fluid from her head. After that she was supposed to have a completely normal life."

RELATED: Grieving mum loses husband to COVID-19 days after delivering premature baby

Doctors continued to monitor Phoebe over the next five months and couldn't figure out why the little girl wasn't recovering the way she should.

"They said the shunt looked okay but something was not right. They checked it three times and in another scan checked the shunt was in the right position.

It was during this scan doctors found a large tumour in Phoebe's head. She was scheduled for urgent surgery the next day.

"The day she had that scan she wasn't allowed to go home and was operated on the next day and didn't make it," Angela says. "She'd been sick the whole time and didn't know it."

Looking back Angela can see how the tumour was impacting Phoebe's life.

"She couldn't sit up and couldn't hold her head up," Angela says. "She was eating solids but wasn't growing. It was feeding her tumour and the more I fed her the more the tumour grew."

In fact Phoebe was still in newborn clothes when she passed away.

"Looking back on photos I can see how big her head was."

It was later discovered that Phoebe had been suffering from grade four glioblastoma, is an aggressive type of cancer that can occur in the brain or spinal cord.

"Regardless of that surgery the outcome would have been the same further down the track," Angela says. "When they did the first scan on her, when we looked back on that, you could see it (the tumour) but it was so little and they were looking at her brain haemorrhage. They weren't looking for it."

The brain tumour hadn't shown up in any ultrasounds ahead of her birth and even on that first scan it was "just a little dot".

Phoebe died in October 2009 and just a year later, Molly was born.

RELATED: 'I thought my headaches were just stress, but it was something much worse'

Angela says Molly came along "in a rush" and from the moment she could walk she's been running.

"Lucy says she can remember Phoebe but she was only two so I'm not sure she knows what was real and want wasn't. As soon as Molly was old enough she understood she had two sisters. It's not something we hide or don't talk about but sometimes it's hard when we have to explain things."

It was about 18 months ago that Molly discovered a man by the name of Andre Jones who was running around Australia solo to raise money for four different charities.

"She was one of his youngest supporters and said she wanted to do something like that for Phoebe," Angela says. "We asked her to hold off until she was a bit older."

They also questioned if Molly, who was only nine back then, could run the sort of distances needed for something like that. Molly wanted to run from Sydney to Canberra as opposed to a lengthy run around Australia.

"We took her for a run and saw she could do those distances, so we began researching different organisations she could help and chose the Children's Cancer Institute."

Molly is busy training for the event, with Angela following along on a bicycle.

"When we do it Molly talks the entire time, making up stories or singing," she says.

Due to the coronavirus pandemic, Molly won't be able to run from Sydney to Canberra as planned. Instead the family plan to run that same distance, 625 kilometres, at a local park in a number of ways.

"We've found an athletic running track and Molly will be running for five hours," Angela says. "We'll even do it in the rain."

The event takes place at Moonee Valley Athletics Track on Saturday 27th February from 8am till 1pm.

Molly's athletics club will be joining in as will Lucy's diving team as well as members of the community.

"Anyone can come down and we have family members in New Zealand doing their own runs and someone from Russia is even running for us," she says.

Show your support by visiting Molly's Facebook page at https://www.facebook.com/mollysrunforphoebe or her fundraising page at Children's Cancer Institute https://www.ccia.org.au/event/mollys-run-for-phoebe/home.