In Utrecht, in the Netherlands, there are Mark, Pieter, Anna, and Eveline. Mark and Pieter have been together for eleven years. Anna and Eveline have been together for nine. Three years ago, they had a daughter named Lotte. The biological father is Pieter. The biological mother is Anna. They are also the two legal parents — Dutch law does not allow more than two names on a birth certificate.
Mark and Eveline are the ‘second dad’ and ‘second mum’. Legally, they are nothing. In practice, they are parents who are involved in Lotte’s life every day: picking her up from nursery, putting her to bed, making decisions about coughs and shoes. Bigger decisions — school, a possible move, medical treatment — are made together by all four.
‘It’s complicated,’ says Mark. ‘But not as complicated as people imagine. The hardest part was agreeing everything before she was born. After that, you just live your life.’
Where this model comes from
Co-parenting between two same-sex couples isn’t new — but it’s becoming increasingly visible. There are several reasons.
First, same-sex couples who want biological children often face practical limitations: donor sperm, donor eggs, surrogacy — all expensive, legally complex, emotionally demanding. Finding a co-parenting partner within the LGBTQ+ community — another couple who also wants children — can resolve several of those problems at once.
Second, there’s an ideological motivation for some: certain couples want their child to grow up with biologically connected adults of both sexes, and find co-parenting a way to make that happen.
Third — sometimes it’s simply life. A deep friendship between two couples becomes a conversation of ‘what if we did this together?’ — and it turns out the idea isn’t as far-fetched as it sounds.
According to Stonewall, one in five same-sex couples considering having children has seriously considered co-parenting with another couple.
Three real configurations
Two couples, alternating homes
The most common arrangement: the child lives alternately between two households. A week with the biological mother and her partner, a week with the biological father and his. This requires geographical proximity — ideally the same neighbourhood, at minimum the same city — and a very clear schedule.
The upside: the child is consistently present in all four adults’ lives. The challenge: any disruption — illness, a work trip, a new relationship — ripples through both households simultaneously.
One primary household + regular contact
The child lives mainly with one couple; the other is actively involved on specific days. This is closer to a conventional shared-custody arrangement, adapted for four parents. Less logistics, but a higher risk that the second couple gradually drifts from parents into ‘visitors.’
Geographically separated co-parenting
When two couples live in different cities — or different countries — the arrangement becomes more complex. The child spends most of the year with one couple and visits the other during holidays. This works, but requires an exceptionally clear agreement and a high degree of trust. It also raises pointed questions about schooling, language, and cultural identity.
What’s actually hard
People who speak openly about their experience of four-parent co-parenting identify several recurring sources of tension.
Different parenting styles
This is the number one source of friction — according to a 2022 survey of 340 co-parenting families in the UK and Netherlands. When the biological mother and her partner are convinced the child should learn to fall asleep alone, and the biological father and his partner sing lullabies and leave the nightlight on — the argument isn’t really about sleep. It’s about whose values matter more.
The approach that people report as working: agree on principles, not practices. ‘We want the child to feel safe’ is a principle all four can sign up to. ‘No nightlight’ is a detail — better left to whichever home the child is in that night.
Unequal involvement
When one of the four adults is stretched thin — overwhelmed at work, going through something difficult, absorbed in their own life — the load shifts. That’s manageable short-term. As a pattern, it breeds resentment.
The hardest part: the legally ‘second’ parent has no tools to demand involvement or limit their own in the way a legal parent would. Everything rests on agreements and goodwill.
New partners
What happens if one couple separates? What if someone meets a new partner who doesn’t want to be part of this arrangement? What if the new partner also wants children — and the child suddenly has a fifth significant adult in their life?
There are no universal answers. But a good co-parenting agreement sets out the rules — what needs to be discussed with the other parties before introducing a new person into the child’s life.
Legal vulnerability of the ‘second’ parents
Mark and Eveline are legally nobody in relation to Lotte. If Pieter and Anna decided, for whatever reason, to exclude them from her life, Mark and Eveline would have no legal recourse. The Netherlands has been discussing the introduction of ‘multi-parenthood’ legislation — it remains at the bill stage.
The UK published a consultation document in 2023 exploring whether the number of legal parents could be extended to four. It’s the first serious legislative move in this direction in Europe. Until such laws exist, four-parent co-parenting leaves the ‘second’ parents legally exposed everywhere.
‘When people ask how we manage, I say: there are four adults who love one child. It’s not twice as hard — sometimes it’s twice as easy.’
What the children say
The first major longitudinal study of children from multi-parent families was published in 2020 in the Journal of Child Psychology and Psychiatry. It followed 65 children aged four to ten who had grown up in co-parenting arrangements (not exclusively four-parent ones, but including them).
Findings: on measures of emotional wellbeing, social adjustment, and cognitive development, these children were indistinguishable from children in conventional family structures. One difference was noted: children from co-parenting families showed greater flexibility in how they defined ‘family’ and were less likely to think in binary terms about what counts as a ‘normal’ household.
The authors were careful to note the limitations: the sample was small, all families participated voluntarily (introducing selection bias), and there are no long-term data on adolescence yet. But the early evidence is encouraging.
In qualitative interviews, the children themselves tended to describe their situation something like this: ‘I have a lot of people who look after me.’ Not ‘I have an unusual family’ — just ‘a lot of people.’
If you’re thinking about this
Some practical observations from people who have already walked this road:
Get to know each other long before you decide anything. Ideally, spend a year — travelling together, disagreeing, making up, seeing how you function under pressure — before committing. You’re choosing people to share the most important thing in your life.
Draft an agreement. In writing, in detail, with a lawyer. Even if it won’t be legally binding in every respect — it creates a shared language.
Agree on what happens if things fall apart. That sounds pessimistic — but couples separate, people move, circumstances change. ‘We’ll figure it out’ is the worst possible answer to questions about conflict scenarios.
Find others with similar experience. Co-parenting communities exist in many countries, online and in person. People who have been through it talk about things no brochure will ever cover.
Consider working with a family therapist — not because something is wrong, but because four adults with four histories and four sets of expectations will benefit from someone skilled in group dynamics.
One last detail
In 2024, Lotte started primary school in Utrecht. All four adults came to the first parents’ evening: Mark, Pieter, Anna, and Eveline. The teacher looked at them, made a note on the attendance sheet, and wrote: ‘parents: 4.’
No questions asked.
Names have been changed at the request of those involved. This article draws on published research and public accounts from members of co-parenting families.