Basically the same problem in Germany. The kid is officially adopted by only one father even so they are recognized as same sex couple by the authorities (in fact the biological mother had to agree that the kid would be adopted by a same sex couple as she left her son for adoption deliberately). This means that the kid get less protection than a normal kid in a family in case of death of the "official in the papers" father.

It will take time for the rules of the society to adapt to the changes in the society.