If this is a much longed-for baby for the both of you why not put your DF down as the father when you submit your paperwork after the birth? For all intents and purposes CSA and centrelink will both "assume" the child is his anyway. Won't he have to adopt the baby once it is born for the birth certificate to be changed?

If you do not name a father on the birth certificate you will most likely have to provide an affidavit explaining why the father is unknown....In the case of AI or IVF through a registered fertility clinic, the mother's affidavit must be accompanied by a letter from the clinic, confirming the circumstances of the child's conception and the anonymity of the sperm donation.

Legislation has changed in many states and the donor is, for all purposes, not considered to be the father - you should really get legal advice on this.

We were looking at DH adopting my son (who, by the way, doesn't have his bio father's details recorded on his birth certificate - only mine). TBH it's
all too difficult for a piece of paper. DH is his father and DS1 is happy - actually he will be "adopting" DH on his 18th birthday.

Oh, and congratulations on your pregnancy!!