Conjoined twins Marieme and Ndeye prepare to start Cardiff nursery

Marieme and Ndeye, conjoined twins from Senegal, are preparing to start full-time nursery in their new home of Cardiff.

Originally not expected to live for more than a few days, they were brought by their father to the UK in the hope of getting a better life.

Now aged three, the girls are continuing to surprise doctors with their progress.

But they have discovered the girls' circulatory systems are far more closely linked than previously thought - so it is now impossible to separate them.

This also explains why they have continued to thrive for so long.

"Doctors now know that they are a very unique and complex case," their father Ibrahima Ndiaye said.

"They are very linked internally and this explains why they have exceeded all expectations.

"They are working together to keep themselves and each other alive and the situation is a little more optimistic."

The new discovery has changed things for the girls.

Back in January, surgeons at Great Ormond Street Hospital in London were considering attempting separation, something which Ibrahima did not want due to the risks involved.

But the new findings show that neither twin could survive without the other and that separation is now impossible.

The girls have separate hearts and spines, but share a common liver, bladder and digestive system.

Gillian Body, consultant paediatrician at Noah's Ark Children's Hospital for Wales, said: "The girls are doing very well.

"They are enjoying a period of stability and constantly surprising us with their progress.

"Last year we thought Marieme was very much dependent on Ndeye, but recent CT scans show they are both dependent on each other for staying alive.

"Long term this means they cannot be separated but in many ways it is nice that they are both dependent on each other.

"This is a big turn-around. Previously the ethics were about could we and should we separate them but now we know this decision is no longer on the table.

"They are now looking forward to school placements and I hope they can enjoy being children."

Although the girls' health is still changeable and their condition described as "life-limiting", this period of stability is enabling Ibrahima to focus on their future.

"My girls continue to grow and bring me so much joy," he said.

"Their speaking is coming along, and they can move with greater independence.

"When Ndeye sees me doing the dishes, she says 'poor daddy', which makes me laugh so hard.

"And when Ndeye is crying, Marieme will turn to her and say, 'Shhh, noisy'."

Currently the girls attend a playgroup for a few hours a week, but from September, they will attend nursery five mornings a week.

Ibrahima said: "It's another chapter opening and bringing hope.

"It doesn't let you forget the situation, but I have learnt that when it is time to celebrate, you should celebrate and see a bright future.

"I can imagine it may be an emotional day for me, seeing them in a uniform as so many times I have thought this day might not come.

"I want people to know about this success as, although we are a private family, so many people ask about them and have taken the girls to their hearts."

As well as looking after the girls, Ibrahima is hoping to set up a charity to help other children with disabilities.

He said: "With this situation and all we have been through, I can't close my eyes to other children with disabilities and complex needs.

"So I am setting up a foundation for the girls, in conjunction with Ty Hafan children's hospice, called Conjoined Destiny.

"If the situation gets worse and they don't make it, I want to put something in place for them to leave a footprint to the world despite our humble and difficult beginning.

"And if they grow to see it, they will know how useful their lives have been."

The Conjoined Twins: An Impossible Decision is on BBC Two at 21:00 BST on Monday and on the BBC iPlayer.