Peter Whitehouse and partner Terri Westwood believe their young daughter Jessica is an angel whose fate is to help save one of her terminally ill brothers.
They hope the unexpected little bundle will provide four-year-old Joey with the vital bone marrow transplant he needs to stop his fatal illness in its tracks. Tragically, her arrival is too late to save older brother Jack, aged five (pictured above, with Peter), who suffers from the same degenerative illness.
The reason the couple, who live in Hately Heath, West Bromwich, believe the four-month-old is special is she was conceived unexpectedly while Mr Whitehouse convalesced at home last winter, after breaking his leg playing football.
"We had noticed Jack's health was getting worse and although we'd talked about having another baby, we had decided to put that on hold until we had discovered what was wrong with him," said Mr Whitehouse.
"But the firm I'd been due to start working for couldn't keep my job open after I broke my leg, as I was going to be off for months, and then a few months later Terri told me she was pregnant."
Jessica was born on November 25, 2005. Three months later, in February this year, Jack was diagnosed with a Metachromatic Leukodystrophy (MLD), a rare disorder which affects nerve endings in the brain.
Last month, after a series of tests at Birmingham Children's Hospital, her other brother - Joey - received the same diagnosis.
At present there is no cure and the only available treatment is a bone marrow or stem cells transplant, which it is hoped Jessica will be able to give, providing she is a good match for Joey's blood and tissue type. Otherwise life expectancy is only a few years, at best into adolescence.
As the couple talk about how their baby girl could save her brother's life, Jack is lying on a sofa watching Dora The Explorer, while being fed via a tube in his nose.
He has to be fed mineral-enriched milk solutions five-times-a-day, sees a physiotherapist every fortnight and also has regular check-ups.
Because MLD is so far advanced in Jack - he has already lost the ability to speak and to chew his food - doctors have said he would not benefit from a transplant.
Joey has not yet developed the full-blown condition and, while his brother watches the television, he bounces around the front room like any energetic toddler does when their favourite show comes on.
As the 24-year-old forklift driver cradled Jessica in his arms, he said: "Jack was diagnosed with epilepsy when he was about 18 months old and we had noticed it was getting gradually worse, so we took him to see his consultant at Walsall Manor Hospital in January who did an MRI scan.
"He sent us to see a specialist at Birmingham Children's Hospital who told us Jack had MLD, which basically means he doesn't have the enzyme needed to break down the fatty deposits on the brain's nerve endings.
"As a result these deposits build up and can affect the ability of messages to get to the brain, which is why it can affect your ability to do things like speak, eat and move.
"The specialist suggested Joey and Jessica should be tested, as it is a genetic condition, and three weeks later we found out Joey had it too.
"This affects about one in 150,000 people and we have two of them in our family. These are like lottery odds but we haven't won the jackpot," he added.
Of those who are diagnosed with MLD one in four will remain healthy, two in four will be carriers only, and one in four will develop the disease.
Miss Westwood, aged 23, admitted a bone marrow transplant for Joey would be "the most amazing gift" his sister could give to him.
The mother-of-three said: "It is hard work but we both love the kids and you just have to get on with it don't you? We've got to be strong for them and each other.
"They're all special and if Jessica can help her brother, that'd be the most amazing gift, I just hope that she's a match and that the operation can be done sooner rather than later."
Mr Whitehouse added: "There's a six-month waiting list for the operation, but doctors at Birmingham Children's Hospital said they'll try and rush them up the list. It's a race against time because we don't know if or when Joey will develop full MLD.
"I am worried about the anaesthetic with Jessica being so young, but doctors wouldn't recommend it if it wasn't safe and this operation will really give Joey the best chance of living a normal life.
"However, if I hadn't broken my leg and been off work, I doubt Jessica would be here, so I do believe it's fate that she came along when she did."
There is still some hope for Jack. He has been put forward to take part in the first human trials of a new enzyme, which has tested well on lab rats, although these are not set to take place for at least another 12 months.
The family are set to enjoy spring break at Disneyland Paris next week, thanks to fundraising efforts of their family, friends and local businesses including PC World in Wednesbury, which raised more than #800 for the trip.
* Anyone wishing to help Jack, Joey and Jessica with donations can contact Mac Cope on 07738 393501