At the time McKelvey described feeling "absolutely sick" in anticipation of revealing her hard work and creative ideas.

McKelvey and Newcastle illustrator and retired paediatric nurse, Kirrili Lonergan, took the opportunity so seriously they even came armed with large illustrations and text.

Fast forward nine years, McKelvey was supposed return to Sydney Writers' Festival later this month, but this time as a published children's author after she was invited to launch her fourth book, Isla's Family Tree.

However, due to the coronavirus pandemic the festival has been cancelled.

"This year I did get invited to read Isla's Family Tree as part of their story time clubhouse," McKelvey says.

"That was an absolute dream come true because Sydney is probably the biggest literary festival in Australia.

"Then to have all of this happen and lose the opportunity and the entire festival altogether was a very sad thing for all the organisers and people who get involved in that.

"Oh well, we'll just have to try again and hopefully they'll invite me back for the next book."

McKelvey grew up in Scone before moving in Newcastle in the '90s to study primary school teaching at the university.

After graduating she worked as a year five and six teacher in schools around the Central Coast and Newcastle before retiring after a decade to raise her children Aidan and Lara.

"I absolutely loved it [teaching] but I decided I wanted to stay home and be a mum for a while with my two kids as I worked pretty hard and I burnt out, like a lot of teachers do," she says.

"I stayed home with the kids, but I missed being creative. Because you can do lovely creative things with kids in your classroom and I missed all that dreadfully.

"So I started looking around for another career where I could still be with children - not just my own - that was creative and flexible."

That led to writing for children's books. McKelvey's first book Dandelions, illustrated by Lonergan, was published in 2015. It explored the relationship between a daughter and her father.

Dandelions was followed by No Bath Week and Up To Something, both released last year.

Isla's Family Tree follows the story of a young girl, whose mother is pregnant with twin boys.

Isla is dreading becoming a big sister, believing her family is already full. However, her mother explains that "families are like trees" and are continually growing.

That leads to Isla's mother mapping out their relatives on the branches of a family tree.

McKelvey says she came across the concept in 2012 when her grandmother died and her son Aidan was five.

"I had to explain to him how my grandmother was his great grandmother, but his grandmother is not my grandmother," she says.

"It all got really confusing, so I thought we need to get our hands on some picture books. I went looking and there isn't much around.

"There's one and that was it. So I thought there's a gap in the market."

McKelvey approached writing a children's book about families using her background in teaching.

The experience of working in schools had taught her that the traditional structure of mum, dad and children was no longer applicable to a host of modern families.

Isla in the story has a pair of same-sex aunties in her family and she also has a heterosexual aunt and uncle who have adopted a child.

Isla's parents are also not married.

"I also haven't discussed where the two children come from in the family with the two aunties and I've left that really open," McKelvey says.

"For the young kids that'll brush straight over, but the older kids might start saying, 'Hang on, that's not quite right'.

"So I hope that does fuel discussions with families, especially with older children as picture books aren't just for kids who are starting to learn how to read, they're for anybody because they set the themes up so they're pretty universal."

As a former teacher McKelvey endeavours to place an educational element in her stories, but she understands it can't be overbearing.

"The educational side of it has to be so subtle that kids don't realise they're learning something and they don't realise there's a message in the story," she says.

"To them, they're just going on a journey with a character."

McKelvey has a fifth children's picture book, Chasing Rainbows, also due for release later this year, but it's currently held up in the printing system in China due to COVID-19. She also has several educational books in the works.

Isla's Family Tree written by Katrina McKelvey and illustrated by Prue Pittock is out now through EK Books.