Wagga funeral director Aidan Vivian and his fiancee Cydonie O'Rourke welcomed their babies Marlie Elizabeth and Matilda Therese to the world after a pregnancy of just 31 weeks.

"They're so tiny. [Marlie] was holding her hand out and you put your thumb over and you cover her whole fist," Mr Vivian said.

Mr Vivian, who has five children from a previous marriage, and Ms O'Rourke fell pregnant with Matilda and Marlie after more than a year of trying with in vitro fertilization treatment.

"We were really lucky, because we had a little bit of money so we could afford to do it. Some people can't afford it so they would miss out on an opportunity like this," Mr Vivian said.

"And no one should have to miss out on it. Because, you know, when you get to hold that little baby at the end, it's just fantastic.

"Once Marlie was in my hands, I did not know anything else around ... I was with my baby girl. And that was it."

Mr Vivian said he was very grateful Ms O'Rourke was able to have the babies at Wagga Base Hospital, where "every man and his dog" rallied in the operating theatre to make sure she had a safe delivery.

"Our big concern was, we've got five kids. If we've got to go to Canberra right now, what the hell are we gonna do?," Mr Vivian said.

Mr Vivian and Ms O'Rourke were longtime acquaintances until a chance encounter at the shops when they were both single led to the blossoming of a relationship.

"We just became a little bit more than friends. We just started to take things further and I introduced her to the kids. And after a little while she she moved in," Mr Vivian said.

Mr Vivian and Ms O'Rourke experienced some heartbreak during their quest for another child.

Late in 2019 Ms O'Rourke went for a pregnancy checkup and found out for the second time she'd lost the baby she and Mr Vivian so desperately hoped for.

They decided to try a third time and found out they were pregnant with the twins in March this year.

"When it came to Cyd having the scan, I was petrified. Because all I kept thinking was, 'Are we gonna have a repeat again?'," Mr Vivian said.

After a few early struggles for Matilda, she and her mum and sister are all doing well at Wagga Base.

They will eventually join Mr Vivian and Ashleigh-Maree, Brock, Maddison, Tailah and Andrew at home.

"I was just built to be a dad, I think. I love it," Mr Vivian said.