As I understand from anecdotal evidence (I.e. i read it on the internet, so it must be true), in the U.S. the guy would be 100% liable as the father, no matter what agreements were made prior, in writing, by a lawyer whatever. Cases of guys being made to pay support where the woman deliberately got pregnant by the guy without his knowledge, and where the guy was told it was his so took on the father role then later found out it wasn't, but becasue he had assumed responsibilty he was legally bound to continue.
No idea on the legal technicalities on Oz, but the guy should be aware that the handshaking (
) agreement may not be worth the paper it's written on, and he could be making a life comittment.
Seems especailly difficult if they are friends so he is likely to have some casual contact with the child, she needs to be aware that somewhere down the line he may start to feel more paternal and have the legal right to be involved, get partial custody, maintenance for the child from her
.
It may seem nice and neat now, but it's people, things get complicated.