If there is one thing every parent wants a long journey with children to be, it's easy. But if you're travelling abroad and have a different surname to your child or children, you might find it's anything but, once you get to passport control.
If you don't share a surname with your offspring, you might be subject to questioning at the border. Or your child might be questioned. Or you might be ordered to produce additional official documents to prove that you are, indeed, parent to your child. Of course, you'll only be able to have all these documents if you knew you needed them in the first place.
This is an issue which is increasingly affecting parents in the UK – and the vast majority of these parents are likely to be mothers. More and more couples are choosing not to marry – as many as two million children are living with unmarried cohabiting parents – and one survey revealed that the children take the mother's surname in only 4% of cases.
Of course, other parents do marry, but sometimes the mother chooses to keep her name. Women who divorce, then re-marry to take a new name, will also face the issue unless they change their children's surnames too.
Helen Perry, a mother of two, wants to put a stop to thousands of mums being delayed or feeling harassed at border control.
Tired of being stopped at borders herself, having remarried, she set up the Parental Passport Campaign. It's seeking to implement a simple change to children's passports, so they include parents' names (with an opt-out for parents who don't agree).
"We commissioned research by YouGov, which showed that as many as 600,000 parents could have been stopped and questioned in the last five years," Helen says, "and I speak to so many mothers who have encountered problems, I'm very rarely in a social situation when I don't come across a mum who has experienced it."
Helen was first questioned four years ago, when her children were aged four and six, coming into the UK from South Africa. "I gave the officer the passports, and she asked what my relationship was to my children. I said I was their mother, and when the officer asked me how I could prove that, I told her she could ask my children.
"She thought I was being terse, but genuinely that was my only option. The situation got quite tense, my daughter started crying. In the end the woman told me she would let me through on that occasion."
A quick request on Twitter for mums to share their experiences revealed that this scenario is, indeed, commonplace.
The mums I spoke to who were questioned at border were all very supportive of vigilant checks which could prevent trafficking or child abduction – but many felt rattled because they had been grilled.
Julie Cohen, an author who's written about unconventional families in her latest novel Dear Thing, kept her maiden name when she married, and her seven-year-old son (who took his dad's name) has dual citizenship. She travels regularly with him to the USA.
"I'm questioned about my relationship to my son at airports and other border crossings every time I travel with him, without my husband," she says.
"They're usually friendly, and since my son has been old enough to ask, they usually ask him one or two questions. But when he was only four, and they asked him 'is this your mummy?' that really confused him."
Libby Watson isn't married to her partner, but was with him when they were travelling home from Switzerland with their twin girls a few years ago. "Damien was holding one of the twins, and went to show both their passports while I held the other," Libby says.
"The man looked at both the twins and beckoned me. He said 'are you the mother?' I said that I was and he replied 'nothing proves you are their mother'. Then he told me I need to take their full birth certificates every time I travel with them, to prove who I am.
"He let us all through, but it shocked me, as I'd never thought about it."
Hannah Martin says she got a 'grilling' by immigration at Gatwick, when she was travelling with her son, and thinks the fact he is mixed race added to the complications.
"My ex-husband is Indonesian. We got married four days after 9 11, and I didn't want to take a surname that started with 'bin' at that time. So we came up with a new surname – Martin – and that was the name our son took.
"As my passport was only two years old, though, I didn't bother changing it from my maiden name. So when I was travelling with my son alone – who looks very Asian, and also has an Asian first name – I guess it didn't make sense to the officials why we were together.
"I didn't have my marriage certificate with me to prove the connection between our names, but luckily I'd given my son my maiden name as a middle name, and that helped to convince them.
"They were polite, but it was unnerving – especially when I knew they had the power to stop us travelling. My son was just a toddler then, so too young for them to ask him anything. But even though he was clinging to me and clearly comfortable with me, it made no difference to their questioning."
One reason why Helen thinks the change to children's passports is necessary is that people are being given conflicting advice.
"When I returned home after being questioned the first time, I tried to find information for women in my situation, but anything concrete was hard to come by," Helen says.
"One source said I should be carrying no less than seven legal documents with me – including birth and marriage certificates, and proof of my divorce from my first husband.
"I've been stopped three times since then, and been told different things. Border officials are confused – one said the law had been changed since the disappearance of Madelaine McCann, but that's not true."
Julie's varying experiences fit. "I've been told several times I need to take my son's birth certificate with me. Sometimes I've been told I need my marriage certificate. And two or three times I've been advised to travel with a letter from my husband, giving me written permission to travel alone with my son.
"I think this is ridiculous – how easy would it be for me to write that letter myself, if I wanted to?"
With so many people being stopped and questioned (which is simply representative of a modern society where co-habitation and blended families are the norm), clearly there needs to be more awareness among parents who want to travel with their children.
But is changing passports necessary? Couldn't Helen just run a campaign to make parents more aware of the paperwork they'll be required to show?
"It's crazy that a parent should have to carry all that precious legal documentation.
"The Home Office response to my campaign was that a passport is a document for travel and that its fundamental purpose would change if it were to be used to identify a parental relationship. But everyone uses their passport to prove who they are."
It does seem a strange response from the Home Office. After all, border controls are making it very clear that identifying a parental relationship IS necessary when travelling, so why not identify that relationship on the travel document?
Moreover, when considering the safety of children, Helen's idea makes considerably better sense to me. If mothers are currently being questioned, and then let through 'just this once' without the additional documents, how effective can the system really be? It seems somewhat hit and miss.
"The fact is," Helen says, "the current system is not fit for purpose. When children were taken off their parents' passports and given their own, 16 or so years ago, the world was a different place.
"Now it's much more likely that a woman will keep her maiden name, or not marry, or remarry to create a blended family. Our passport system needs to reflect modern families.
"Our borders would also be safer and more efficient as a result of this change – if it goes through."
Also on HuffPost: