According to reports, the couple have never lived together but enjoyed a short relationship in 2013.
As a result of this, they welcomed a baby boy together.
The pair have agreed to share custody of their child, and have been happy to both take on parenting duties.
But there has been a dispute over how the little boy should be known.
Ms Reynolds wants her surname used, but Mr Sherman wants their son to have a double-barrelled surname.
To date, the boy has not had his name formally registered - and he is now two-years-old.
The former couple attended a trial last year, where, according to The Guardian, the judge ruled: "The child has two parents and I consider it is in his best interests to have a hyphenated surname."
She instructed the parents “to use the surname [Sherman-Reynolds] at all times, both in writing and orally when referring to the child’s surname”.
However the boy’s mother has since appealed that decision - and the court has been forced to uphold that appeal.
The judge said on accepting the rehearing: "We consider that a dispute about the name by which a child will be known perhaps for his entire life is a matter of real importance."
Stock images used throughout.