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.’
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.
According to Stonewall, one in five same-sex couples considering having children has seriously considered co-parenting with another couple.
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 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.
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.’
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.
People who speak openly about their experience of four-parent co-parenting identify several recurring sources of tension.
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.
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.
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.
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).
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.
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.’
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.
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.