It was Mr Fan's 30th birthday, and after the morning citizenship ceremony by the lake in the searing sun, the couple was heading to the hospital to care for their premature twin baby girls.

Ms Li had expected she would still be pregnant on Australia Day, but the girls were born at 36 weeks and three days, on January 14. Their brother turned one on December 22.

The couple, from Hunan and Henan provinces in China, were among 29 people from 13 countries to become citizens in Canberra on Sunday. Nationally, 27,400 people from more than 160 nations became citizens.

The ceremony was heavy with formality, soaked in solemnity and punctuated by the roar of an FA-18 Hornet fighter plane that brought adults to awe and children to tears. The citizens were swept up in suits, ties, frocks and heels, making you think the new emphasis on a dress code that has seen some councils ban shorts and thongs was surely unnecessary, at least in Canberra.

While thongs were out, references to Vegemite, barbecues, Tim Tams and wombats were obligatory.

Prime Minister Scott Morrison and Governor-General David Hurley spoke and posed for photographs with each new citizen, many of them in family groups.

Pakistani family Rao Asim Gohar, Hina Asim and their daughters had planned a big family celebration of their new citizenship, but instead decided to donate their celebration money to the bushfires.

Sinead Clarke and Tony Seel, from Ireland and Liverpool, have lived in Australia for six years, having upped sticks in an economically depressed Dublin for a long-dreamed-about new life in Australia. Ms Clarke said they had never been to Australia when they brought their boys, then aged 10 and 7, to Canberra to live. Such was the state of Ireland's economy that Ms Clarke believes her boys would probably have had to emigrate for work in any event.

"We packed our bags, sold our home. It was very exciting," she said. They found "a brilliant country, with a brilliant future for their boys" with oldest son Daniel, now 17, starting college and planning an engineering career.

Ms Clarke works at ACT Health, Mr Seel works in construction, and the family lives in Kambah.

They left behind parents and siblings, and Ms Clarke feels that loss, but says Australia has given them a different lifestyle.

"What's not to love?" she said.

Mr Fan and Ms Li came as students and met at the University of Canberra. They rent in Coombs and run a private cleaning company together.

In more good news for the family, Mr Fan's parents got news of their permanent visas being granted just four days before Sunday's citizenship ceremony. Ms Li's mother is visiting to help her daughter with the new babies; her father is too ill to travel.

Asked about the geopolitical ructions that are unsettling Australia's relationship with China at the moment, the couple say simply that the cultures are totally different.

"We think here is a really peaceful place," Ms Li says. "The life here we enjoy. The environment here we enjoy. And the people here we enjoy."