Gaby Eirew suffered two big bereavements in the space of a month. The experience impelled her to find a way of prompting parents to record video messages for their children.

When Gaby Eirew's father was dying from pancreatic cancer one of his last pieces of advice was: "Grieve for me for two years, after that you're grieving for yourself."

She thought she would be good at grieving. After all, she had worked as a counsellor dealing with cases of childhood trauma.

But she found herself struggling more than she had expected.

To make matters worse, she and her husband had recently moved from London to Vancouver with three young children, meaning she had no support network.

Feeling fragile, she tried to ring a close friend from childhood, Emma, a doctor in London. But then she got some more unexpected news: Emma had died suddenly and unexpectedly.

"She was clever, beautiful, hard-working and warm," recalls Gaby. "I was small and wacky and she was this graceful intelligent person. Somehow we liked each other."

Her friend's death plunged Gaby further into grief. "I had no idea what to do with myself," she says.

Both Gaby and Emma were 39 at the time. Emma's three children were all 10 or younger - like her own. Not only was Gaby now experiencing her own grief, as a friend and daughter, she couldn't stop thinking about the impact of a parent's death on young children. How do you begin to explain it to them?

"I imagined my kids like hers, growing up with everything that they knew directly from their mum stopping there and then. I wanted to write to them all and reassure them and tell them the most useful things, but I could not sum her up. Some things I realised the children would hear from their father and grandparents, but some things would surely have to come straight from her?"

For weeks she felt "like a lunatic", obsessed by death. She kept asking friends and strangers she met: "What have you prepared for death?" It was her favourite topic of conversation.

Looking back, she sees it as part of a recovery process and a need to channel her pain into something practical. The eventual result would be a tool to help children mourn their parents - a free app that has been used by tens of thousands of people in more than 30 countries to leave a legacy of video messages for their families.

In the summer of 2008, a few months after her double blow, Gaby began a study of bereavement.

Over the next five years, she interviewed more than 100 people in Canada and the UK who had lost one or both parents as children. (In the UK about one in 20 children will lose a parent before the age of 16 - approximately 24,000 each year.)

She found them by posting notices on online forums, and leaving physical notes in swimming pools and libraries.

"I spoke to people born after their dads died, or came home to a crime scene, or were in car accidents that killed their parents," says Gaby.

She found that breastfeeding her son at bus stops was a good way to strike up conversations with strangers about parenthood and mortality.

She asked these people what they wished they could have asked their parents.

"The single most important thing that people said they wanted to hear was that their parent was proud of them, that they loved them and to hear them say that with their name," Gaby says.

"So often people were told that their mum or dad loved them so much, but they needed and wanted to hear it."

Sometimes they wanted to hear a very specific set of words.

"They wished they could ask their parent, 'I remember you whispering something to me every night, what was it? I want to hear it again.'"

It could have been a prayer, or nursery rhyme or other words that became part of a nightly ritual and helped them know they were loved before they fell to sleep.

So one key aim was to get parents to record that simple message in video form for posterity. Gaby's app, called RecordMeNow, is essentially a series of prompts that helps people to create a video library for their children, broken down into subject areas, based on Gaby's findings.

Another discovery was that bereaved children often carry a huge amount of guilt. "For a parent to say in a message 'I'm sick, I'm dying, it's not your fault, I don't want to die, I'm happy you get to live on and you get to have a full life,' that's really important."

However, Gaby was also surprised to hear many of the more mundane - and quite specific - questions that children had for their parents.

What floor cleaner did you use? That smell reminds me of my childhood. What perfume did you wear? I want to wear it too. What were your middle names? What is the recipe for that soup you used to make? What is that walk we did? I want to walk it now with my child and think of you. Show me how to shave.

Satisfying children's curiosity about these kinds of details can really help with grieving, she says.

But they also wanted to hear about other parts of their parents' lives. Things like a memorable story from their childhood, a story about romance, or what it's like to go through puberty. How did they choose their job and how did they handle stress and anger? Did they have any suggestions for naming their children?

Essentially, they were looking for advice and guiding principles that would help them make important decisions as their lives unfolded without their parents.

Gaby also realised that they didn't want to hear the kind of sugar-coated, idealised accounts of their parents they had heard at funerals and family gatherings - they wanted raw stories, warts and all, that they could relate to.

That's why the app encourages you to talk about difficult times, says Gaby. "You need to be a three-dimensional person, not a big walking success story, which is too much for anyone to live up to. You can be troubled, that's OK, that's part of life and that will help your children when they have a difficult day."

There were also queries that reflected a child's lack of understanding about death, says Gaby.

Some people looked back on their childhood and said they "didn't understand why Daddy was buried but we've still got his wheelchair, how can he be without it in heaven?"

So one question prompt in the app to the dying person is simply: "How do you view death and dying? What do you think happens after death?"

The app is designed to be simple with "no bells and whistles" says Gaby, because when you are diagnosed with a terminal disease, you suddenly have millions of things to think about, including work, wills and other financial matters, and a short time-frame to act on them.

Your mind can be all over the place and the app should help you to focus on this important, but daunting, task.

Two large communities of people the app has helped are those who have been told they have terminal cancer, and those diagnosed with Motor Neurone Disease.

People like Dean Mucklow, who lives in Birmingham.

Dean first realised something was wrong when he struggled to do up the poppers on his daughter's Babygro.

He was 42 and on paternity leave with his second child.

He had been occasionally dropping objects, which worried him, but he put this down to his regular hobby of karate, which he thought might be affecting his hands.

Eventually though, he decided to visit his doctor, and was diagnosed in 2013 with Motor Neurone Disease (MND) - a disease that affects the brain and spinal cord, often progressing rapidly and leaving people locked in a failing body.

"It's really hard to get your head round. You're not feeling poorly. When you try and move it's like having massive lead weights on your arms, your legs, your neck. You get to think a lot," he says.

The worst thing is the frustration. He wants to play with his children, but he can't.

These observations were made by Dean in videos he made with the RecordMeNow app in 2015.

After his diagnosis, Dean and his family were put in contact with Alison Noakes, who works with the Motor Neurone Disease Association. She recommends the app to people if they still have good voice quality because she has seen the benefits it can bring.

People can feel very anxious when they first get their diagnosis and the app gives them something positive to focus on, says Alison.

Dean used RecordMeNow to create an archive of more than 80 video messages for his family, including his young son and daughter, while he could still speak.

In some he tells his life story, including lessons he has learned. These make clear that the diagnosis was cruel timing. Dean was just beginning to reap the benefits of his life's hard work: a successful career, wife, home and children.

He left school in 1987 and worked in a factory for many years, but eventually enrolled part-time in a college to study Information Technology.

He then trained to become an engineer fixing photocopiers and cash machines. That led to a job at electronics firm, Ricoh, where he rose up the ranks, eventually travelling around the UK managing a team of trainers.

Hard work and dedication are the key ingredients to getting on in life, he says in one video.

This is what he said when prompted by the app to answer the question, "When were you most scared?"

I was scared walking down the aisle to marry your mum. I was scared but it was the best thing I ever did. I was scared to have children. As soon as you have children you never stop being scared or worried. Scared makes you alive. So embrace it, use it. Never let it stop you.

He also shows his children one of his special skills in one video: touching his nose with his tongue. All while wearing his beloved Aston Villa football shirt.

In another, he says:

This is the hardest thing I've ever done in my life, trying to find the right words. I love you all, take care and keep smiling.

Dean now communicates through a computer, using eye movement.

He "banked" his voice before he lost it, preserving phrases, words and sounds in a digital database. Thanks to this, when he composes words using his special software, it is played out on a speaker attached to his wheelchair, in a computerised, synthetic version of his voice, complete with Brummie accent.

Reflecting on the video messages, now that he has lost his capacity to speak, Dean says: "I always wanted to leave some kind of history for my kids. Especially for my youngest as she has only known me this way. I used RecordMeNow because it was in the format I wanted with loads of questions and the option to add other questions.

"I wanted my kids to have somewhere to go if they ever think to themselves, 'What would dad think?' They'll always have a recording of my thoughts and opinions. It's been so beneficial knowing that my kids will see the real me. Hopefully I can pass on some advice."

Dean's son and daughter are aged 10 and six. He doesn't think they are ready to see the videos he has made yet. He just wants them to be available for them when the time comes.

Alison Noakes of the Motor Neurone Disease Association says RecordMeNow is part of a bigger trend of people with terminal conditions thinking about their digital legacies, including what to do with social media accounts.

But "legacy work" has a long history in palliative care, she says. She's familiar from working in hospices over the years with the idea of "memory boxes", in which patients left toys, CDs or perfume bottles, along with stories about why these physical objects were important to them.

RecordMeNow is like a digital update to this idea, she says.

Alison has even been inspired to record her own messages using the app, though her children are already adults and will have plenty of memories of her.

It forces you to examine yourself and the results can be surprising, she says.

"When you recall details like the name of your favourite childhood teddy, you suddenly realise, that's information that would otherwise die with you."

Of course it was possible to record messages before the age of smartphones, using video cameras or cassette tapes.

Some parents who knew they were dying left messages for their children to read on specific occasions, like Christmases, birthdays or weddings.

But Gaby's research found it was better to create a resource bereaved children could dip into at times of their choosing.

"Respondents said to me, 'My wedding will be emotional enough without my mum or dad, I really don't want to open a message on that day, I don't know how I'd respond.'"

In fact, if the children are old enough and in a strong enough state of mind when the parent is dying, they can adapt the prompts in the app to get the kind of memories they want.

One child wanted a video of their parent watching him play a football game, recalls Gaby.

Gaby has close relationships with many hospices and palliative care units, which use her app with patients. She knows from her own experience that often people want to record messages for posterity, but leave it very late.

Sometimes they leave it so late that they can no longer physically do it, so she has to help out and record the video herself.

"I've been called by the husband or nurse, and I will step over a tiny baby in a cradle or a car seat and the mum will be dying that day. That is very kind of her that she still wants to record a message, but very far from ideal."

It's a shame that in their final months people often focus on financial matters instead of leaving "something emotionally supportive", says Gaby.

In fact she would like every parent to make a video, in the event of an unexpected accident taking their life, something she calls "an emotional insurance policy". (The app is free, so she doesn't benefit.)

She has taken this precaution herself, for the benefit of her three children.

"I have seen so many people who have died and I am getting older, so it's feeling increasingly real to me," says Gaby.

Her children were aged one, four and seven when she began her recordings.

"I chose key stories that are extremely happy or funny or tough and speak to a core characteristic of that person, or our relationship. As I talk, I imagine my children at all different ages and scenarios and want to be loving and supporting to them, whatever they are going through.

"I tell very clear stories. I laugh or cry throughout - that is OK."

She's made messages about family rituals, like all climbing into bed together every night to read the chapter of a book.

Or the time she made her family wait in the rain to watch a cow give birth, before realising it was just stuck in the mud.

But she also talks about romance, a subject she found many bereaved children found difficult to broach with their parents, but wanted to know more about.

"I talk about going out with my husband who was my good friend for many years and how I suddenly knew we should be together and went to his home at 5am, and just sat there, totally ready for life with him.

"I try to talk of interesting things each child did or said at certain times. They are snapshots, to say I care, I noticed."

She thinks every parent should make these videos every five years or so.

Although keeping your composure can be hard in a video, Gaby says the medium has advantages over audio when it comes to grieving.

Some people feel they are not looking their best, but children don't care about that, she says.

"I have footage of my dad, and just the way his eyebrows twitched a bit when he found something funny, it's like… uuuh... yes, that's him."

In time, video becomes especially valuable for young children who are bereaved because there is a huge amount of hurt associated with not being able to remember what your parent looked like, says Gaby.

The videos can help you trust your memories.

Though Gaby Eirew lives in Canada, she has kept in touch with Sky, the eldest daughter of her friend, Emma, whose death inspired the RecordMeNow app.

The pair met in person in December, for the first time in a few years. Sky is now 21 and a university student.

The meeting was a chance for Gaby to tell Sky stories about her mum. Gaby's friendship with Emma blossomed when they were around Sky's age, so the stories become more relatable.

Sky is the oldest of three siblings and was 10 when her mother died.

Her earliest distinct memory of her mother is during a skiing holiday, when she was six years old. Sky fractured her collar bone during her final ski lesson and was taken to hospital by her instructor. She recalls being "so scared" and wanting to see her parents. She has an enduring image of her mother running to the hospital, frantically trying to find the entrance.

She thinks she can remember some bath-times too.

"I was lucky in that as the oldest I have the most memories," says Sky.

"I remember when I was told [about her death] I had a flash forward of my life, thinking she's not going to be here then, she's not going to be here then… the hardest part is accepting that."

Recalling her mother's death and the impact it had on her family brings Sky to tears.

But after a pause she regains her composure.

"One of the best pieces of advice I was ever given was from my dad. It is that you should never be afraid to cry and show that you are hurting, because you are, and you are too young to hide it. That helped an awful lot.

"It's easy to think, 'I hate the world, this is so unfair, why has this happened to me?' And you have every right to think those things."

Here the RecordMeKnow app can help, she thinks.

"Half of the fear is thinking, 'I am alone,' and having the app is like having a little safe haven, allowing you to celebrate your parent's life as opposed to grieve their death."

Small details, such as what make-up they liked to use, would be nice to know, she thinks.

"It's the little things," she says. "You'd be surprised how small stories can make such an impact, so you feel they are still with you, or you are part of their lives."

And at a simpler level, the app would just allow you to just listen to their voice again, says Sky. "One of the things I found most scary was forgetting how they sounded, how they spoke."

There is another reason that Gaby is driven to spread the word about her app.

"I was raised by someone who didn't know who she was," she says.

Gaby's mother, Denise Paluch, now 82, was a child of the Holocaust.

She was smuggled out of the Drancy camp in France by the French Resistance in 1942. Her parents - rounded up for being Jewish - were sent on to the Auschwitz concentration camp a few days later.

Because she was only four years old when this happened, Gaby's mother has very little memory of her parents.

She lived her early childhood in Lyon under the protection of a woman who ran a school for children with special needs - she still calls this woman "my French mother". Denise was given a false identity to protect her in Vichy France.

She was also given a fake postcard pretending to be from her parents, saying that if she cried for them, they would not come back. This was a way of protecting her, because it was feared that if she displayed any emotion about her parents it would draw attention to her true Jewish identity, and put her life at risk.

Grieving, or any attempt to emotionally process the absence of her parents, was not permitted. It was life-threatening.

Denise spent her teenage years in South Africa, living with an aunt. Aged 15, her grandfather gave her a few pictures of her parents, the first time she was able to see what they looked like.

In later life in the UK, she married and raised four children, including Gaby, still without knowing her parents' fate.

It was only when she reached her 50s that records were discovered that confirmed her parents were sent to Auschwitz and died there. Only then could she accept she was an orphan and begin some kind of delayed grieving process.

She visited various places with Gaby, such as her parents' home in Brussels, in a desperate bid to corroborate memories. One breakthrough was finding some distinctive wall tiles she remembered, that she would have gazed at from her pram.

Recalling these events after so many years, the things that bring tears to her eyes are the fact that she was deprived of an education and that she was given away by her mother, something she says she felt more acutely after having her own children.

"The saddest thing for me, looking back, is the feeling of rejection," says Denise.

"I thought she didn't want me, therefore she went one way and I went the other."

This might seem strange to someone learning about her story for the first time, who knows the historical context. But you have to see things from a child's perspective, says Gaby.

The trauma of rejection at such an early age leaves a deep scar, even though the only reason Denise's parents took this heart-wrenching step was to save her life.

It worked, and something of them now survives in Denise's 11 grandchildren.

One of Denise's most precious objects, hanging on the wall of her north London home, is a sepia photograph of her mother, aged about four.

"She would have been roughly the same age in that photograph as I was when she gave me away," says Denise.

"I'm so proud of what Gaby's done with her app, because it will help so many people who don't remember their parents, to feel like somebody's child."

So what question would she ask of her parents, if they had had access to the app their granddaughter, Gaby Eirew, has created?

Without hesitation Denise knows the answer.

"What colour were my mother's eyes?"