They who live together, fight together.

And now, the family affair of Australia's most prominent taekwondo athletes has just become a little bigger.

Olympians and fiances Carmen Marton and Safwan Khalil are preparing to compete at the world championships in Mexico in July, after qualifying on Sunday.

They'll be accompanied by Marton's sister Caroline, 28, and brother Jack, 20, after the siblings also successfully made the Australian team in their respective divisions.

The clan will be the nation's first trio of siblings to compete at a world championship level.

For the couple who spent the London Games training together under coach and Khalil's brother Ali, it's an exciting prospect to expand on their family affair.

"It is a dream come true to share this experience with my siblings," 26-year-old Carmen Marton said in a statement on Tuesday.

"I wanted to cry when we all qualified. To be on the same Australian team, I am just so proud.

"We never gave up after all these years. We did it!"

Marton, who placed fourth at the London Games, said she was nervous about her return to competition following her disappointing finish at London.

But now, there was added anxiety with her younger siblings competing too.

"I felt sick watching my siblings fight to secure their places," Marton said.

While Marton and Khalil failed to cap off their Olympic campaign with a gold medal, the couple are hoping to end the year with another type of gold.

They were expected to exchange vows last December but have temporarily put the wedding aside to focus on competition, with an eye to the 2016 Olympics in Rio.