My daughters, Greta and Aurora, may only be eight and seven, but they know this to be true: a donor isn’t a dad. As donor-conceived kids they have been taught that they have a donor, a special man who helped me become a mummy, but he is never referenced in any way as a father – because he’s not.

Legally he is not their father: his name isn’t on their birth certificates and he has none of the rights and responsibilities of a father. Emotionally he is not their father either: the kids have never even met him.

I understand it’s easy to casually confuse donor and dad. I often hear friends and family say things like “Greta and Rori’s father is a donor”, and I always correct them. No, they don’t have a father. They have a donor.

Australia's high court rules sperm donor is legal father of child Read more

While it’s not always immediately apparent why it’s important to draw a distinction, it is.

If the donor is a father, where is he? Insert feelings of rejection and abandonment. Also, one day they might choose to meet their donor, and for a successful outcome all parties will need to be clear about their roles and expectations.

Repeat after me: donors are not dads.

But then, last week, the high court of Australia delivered a decision that turned that presumption on its head.

The case involved a dispute between Robert Masson and Susan Parsons (court pseudonyms). Masson and Parsons had been friends for decades when in 2006 they agreed to create a baby. The arrangement was private and informal.

Masson was listed on the birth certificate, and although the child lived with Parsons, Masson played an active role in her life. She called him “Daddy”, had sleepovers, and he attended school concerts and other activities.

Then Parsons and her wife, whom she met and married after the child’s birth, decided to move to New Zealand, and Masson took legal action to prevent being separated from his child.

In 2017, the family court handed down its decision recognising Masson as a legal parent based on the Family Law Act 1975, noting Masson’s intention at the time of conception and his subsequent involvement in the child’s life.

The mothers appealed to the full bench of the family court, arguing that actually state law applied in this situation (NSW Children’s Act 1996), citing the section that states that when a woman conceives a child via a fertilisation procedure with a man who is not her husband, that man is not the father.

The full court agreed and Masson was presumed not to be the father.

What the courts in this case were actually debating was the question of which jurisdiction creates the laws on donor conception: state of federal?

Masson appealed to the high court, which last week ruled that he was the child’s father, based on “the ordinary accepted meaning of the word parent”.

The high court has ruled what it deemed to be in the best interest of the child, a standard that is applied in disputes around parental roles and donors in most western countries. Put simply: the child considers Masson to be her dad.

But what does it mean to the donor conception community?

Essentially, the definition of parents has been found to include sperm donors, as long as they meet the definition of “parent”.

What this doesn’t mean is that all sperm donors are now considered dads. There is no need for sperm donors to freak out that their offspring will show up demanding inheritance and to call them dad, and there’s no reason for mums to fear a stranger suddenly demanding contact with their child.

In the case of my daughters, Greta and Aurora, their sperm donor is unknown to us and has never played any role in their lives at all, let alone parental roles.

It’s a different story for those families who have used known donors – and that may be troubling for the thousands of Australian families who have relationships with their donors.

The accepted wisdom is that knowing their donor and having some connection with them can greatly benefit a child’s mental and emotional development.

The concern is that following the high court decision, parents may limit, cut off or deny relationships with the sperm donor for fear they may at some stage assert their role as parent.

At the very least, this case is a cautionary tale about the dangers of entering into private and informal parenting agreements with friends.

Sperm donor takes fight to be recognised as child's legal father to high court Read more

I felt very safe and comfortable accessing donor sperm through a clinic because I knew the clinic had covered all legal bases.

My children’s sperm donor has been counselled and has signed documents stating that he understands that he is donor and the rights and responsibility that entails. I also had counselling and signed documents. There are no grey areas.

Although, it must be remembered that prior to same-sex couples and single women being allowed access to donor sperm programs in 2010, private and informal arrangements were one of very few options open to these members of our community.

If this court case has shown anything, it’s the need for greater clarity around the definition of what constitutes a “parent” in an age when it can take three people to make a baby, and many more to raise them.

• Margaret Ambrose is a journalist and editor of The Baby Project