I know this is a really late reply, but I thought it might help someone.

I dont know what its like in QLD, but in NSW you can change your childs name without have to go through the adoption process.

I met my (now) husband 2 weeks after a drunken one night stand. At the time I was not aware that I was pregnant. I only know the biological sperm donors first name so have no way of finding him. Quite frankly, I dont want to have him involved in our lives.

My DH and I got married in January of this year and we changed my DD surname from my maiden name to my DH surname.

Eventually we will go to the family court for an intrafamily adoption (where one biological parent remains a legal guardian). But right now, we are just happy with having our surnames match. No one knows that she is not legally his, and she even looks like him! She is 4 now and has only ever known my DH as Daddy. Her birth certificate has no father listed. Works for us. Thats my 2 cents.

Cheers, Suzie.