Alyssa Nolan leads prayers for conjoined twins Trishna and Krishna

Sadly, Bethany died 16 hours after surgery.

Alyssa, who has had 40 operations to correct problems since her own separation, has epilepsy, mild cerebral palsy, recurring kidney problems and developmental delays.

She had been through the worst of it, but would still need more surgery down the track, her mother, Mary Nolan, explained.

"But on the outside, to look at her she's just a very outgoing, very bright - socially, anyway - very talkative, bossy, beautiful eight-year-old girl. She's certainly the diva of the family," Ms Nolan said.

The Brisbane mother had no regrets about going ahead with surgery to separate her twins. The alternative was to have done nothing, and they would probably both have died, she said.

"So you take those small chances wherever they are," Ms Nolan said.

Ahead of the surgery, Ms Nolan was terrified something would go wrong, but also very hopeful at the same time.

"My girls were quite ill leading into the separation, it was a very stressful time ... but we were filled with hope we might end up with two amazing little girls at the end of it."

Beth had no kidney so going into the separation the family knew her chances would be less than Alyssa's.

"The death of a child, I think, is one of the most difficult things that anyone can face," Ms Nolan said.

In the first few years afterwards, Ms Nolan and her husband, Shaun, were told several times Alyssa was not going to pull through.

"She contracted meningitis from a procedure, she had a bone grafts and plates put in her skull, she had brain fluid leaks, all sorts of scary things," she said.

"But she just faced every hurdle head-on and came through it.

"Every time they said she wasn't going to make it, she just kept going.

"She wasn't going to walk, she was never going to talk, and now we can't get her to sit down or shut up."

Ms Nolan said that as with her daughters, she believed the Bangladeshi toddlers were born with an inner strength and a bond that most of us could only imagine.

"I just pray, and my whole family pray, that they will get them through."

(Edit:Ruby)