Ethan and Ava are Australia's first ever "twiblings”.

A Melbourne couple have made medical history after welcoming Australia’s first pair of “twiblings”.

Siblings Ava and Ethan were born four weeks apart a year ago, and they were carried by separate surrogate mothers – but they were both conceived using sperm and eggs from the same people.

Their parents Sean and Danielle shared their story on last night’s episode of The Embassy on Channel 9.

Ava was carried by a paid Thai surrogate while Ethan was carried voluntarily by Danielle's best friend back home in Melbourne.

Their arrival ended 10 years of heartache for their parents, who had suffered through failed IVF rounds, miscarriages and the tragic death of their 11-day-old son, Aidan, who contracted a bowel infection shortly after birth.

But the twiblings' birth didn't go smoothly - little Ava was born with three holes in her heart, putting her life in danger.

Dad Sean, an IT software specialist, travelled to Thailand to bring Ava home while wife Danielle, a special needs teacher, remained at home to care for little Ethan.

WATCH a clip from the episode below. Post continues after video...

After Ava's frightening diagnosis, an emotional Sean contacted Australian embassy staff to ask for help in getting his daughter home to Australia urgently in order for her to see a cardiologist. They eventually arrived home safely - an had an emotional meeting with mum Danielle at the airport.

News.com.au reported that Australian embassy staffer Trudy McGowan, who assisted Sean following Ava's brith, still clearly remmebers the family's unique story.

“To see him so distraught, and who wouldn’t be when a baby is so sick, and then hear about all that had led up to tiny Ava, how could your heart not go out? They’d been through such a difficult time,” she said.

“At the time, as it unfolded in Thailand, I was just focused on helping Sean and Ava. It wasn’t until I saw the footage of Ava and Danielle meeting for the first time at the airport that the emotion hit me.”

A year on from their children's dramatic births, Sean and Danielle have decided to keep their private lives out of the spotlight.

We wish their amazing little family all the very best.