From jokes about hair loss and holding your breath, to Molly's dad John telling people Miss Australia had tried to crack onto him, they found a way to create a rainbow.

Now back home after 10 months in Sydney, Molly is paying it forward.

Molly wants to raise $46,000 for Ronald McDonald House, the amount it would have cost the organisation to host the Crofts for the 292 nights they stayed.

"I'm paying it forward to other kids so they can help families like ours. Without them who knows where we would have been, it was such a big help," she said.

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In July 2018, Molly was in the middle of three days of representative netball when her shins started to hurt. Before that she had been playing in the polding basketball side.

Her mum Ange believed it was shin splits, so they strapped her up and she continued playing.

Within two weeks she had started chemotherapy.

An MRI had revealed a tumour in Molly's leg and little spots in her lungs. She would have to start weeks of chemotherapy with a 40 to 50 per cent chance it would be successful.

The family wouldn't know if the aggressive chemo had been successful until the 14 week mark when they would open up her leg. If 90 per cent of the tumor had died, the chemo had worked.

"You don't know how you're going, you don't know how it's responding until the operation. And you could be doing it all for not much but there's no other treatment so you have to keep pushing ahead anyway," Ange said.

After the first round of chemo, Molly got out of bed to pick up her phone and her leg shattered because the bone was so weak. She would go on to lose most of her lower right leg, her knee and part of her thigh.

But Molly was lucky. Nearly all of the tumor had been killed.

Despite that, she underwent another 17 rounds of chemo.

Right from the start, the Crofts received some advice they've followed every day, from someone who has learnt a thing or two about getting through trauma.

"Ryan Medley rang right at the beginning of the journey and said 'Ange, just make sure no matter how hard the day gets, try and tell her to look for a reason to smile every single day'," Ange said.

"We used to say 'what's the rainbow today?'"

Ange said there were three things that got the family through: looking for a reason to smile, the love they received from Dubbo and Molly's sense of humor.

Having somewhere to stay together also made an incredible difference.

The first two nights at Westmead, John and Molly's sister Maddi slept in a "broom closet" at the end of the ward.

John didn't know there was an alternative until one of the nurses mentioned Ronald McDonald House.

"I walked across, knocked on the door and said 'do you have a room?"

Ronald McDonald House provides a place for families to stay when they have a child undergoing treatment at the Children's Hospital at Westmead.

John said from the start, the family wanted to stay together. Even Maddi was flying between Dubbo and Sydney to try and complete her schoolwork while being there for Molly.

"All of us wanted to be there the whole time. They told us from the start that it was a 40 to 50 per cent success rate but even 99 per cent wouldn't have been enough," he said.

Ronald McDonald House allowed the family to focus on Molly's healing. Ange and John who are both self-employed walked out of there jobs in Dubbo and didn't go back.

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The staff, volunteers and other patients at Ronald McDonald House became family for the Crofts.

"They were there with you every day. They'd see you walk back from the hospital and go 'what's going on with you today?' They've experienced our darkest days with us," Ange said.

Meanwhile, John became both the resident prankster and the back-up handyman.

Molly said one day swimmer Leisel Jones visited with her gold medal.

"The Ronald McDonald lanyard was red and so was her gold medal. Dad gave her the lanyard back and kept the medal," she said.

Then after 10 months, things changed.

"One day you're fighting for her life still and the next day a doctor walks in and goes 'she's amazing, go home'," Ange said.

"Hopefully forever, but definitely for the minute, the fight is over."

Now back in Dubbo, Molly has a peripherally inserted central catheter (PICC) line feeding her antibiotics. She goes to Dubbo Hospital every day to have the bag changed and every three months for the next three years she'll head back to Sydney for another PET scan.

All of the family is learning to adjust to their normal again.

Soon Molly will go back to getting her leg to bend again at Ryan's rehabilitation facility Active - On the Move.

It's inspired her to become a physiotherapist and help others fight similar battles.

Ange and John are still trying to find a way to say thank you to everyone who has helped them.

"I get anxious going to the supermarket now because of the love everyone has shown. I'd hate to walk past someone and not stop and say thank you," Ange said.

"How do you say thank you? It's a couple of simple words but it doesn't seem enough. But actions speak louder than words, that's why we're paying it forward."

Molly's Mission has already raised more than $8,000 - or 50 nights. Molly is confident she'll be able to get the whole amount.

Like the Crofts, the donations will help give a family somewhere to stay if a loved one is in Westmead Hospital.

A few nights ago, Molly reflected on the last 10 months with Ange.

"Just before I put her to bed she said 'you know Mum, it hasn't been that bad'. She said 'I thought when I was first diagnosed I was never going to get through it but I've met some amazing people'," Ange said.

To donate to Molly's Mission visit: rmhcgws.org.au/molly.