The Prime Minister's sister, Christine Forster, is engaged to her long term partner, Virginia Edwards - but admits that with debate raging over same sex marriage, "It might be a long engagement."
The openly gay City of Sydney Liberal Party councillor proposed on a trip to Broken Hill and plans to marry surrounded by close friends and family in her home city, "hopefully under a federal marriage act".
"It's a bit difficult, really, because we've decided we want to get married here in Sydney, hopefully under a federal marriage act but it might be under a NSW act. It's where our friends and family are. For us it's really important that we are married in our home and that our marriage is recognised in our home, which is here."
Her brother and national leader of the Liberal Party, Tony Abbott, does not support same sex marriage and has said he disagrees with those in favour of legalising gay marriage.
While a group of cross-party MPs have drafted a same-sex marriage bill for introduction into the NSW Parliament, no date has been set for its introduction.
Ms Forster, a mother of four, said she will only start making concrete wedding plans when she is able to enter a legal union, and believes a change in law is a question of when, not if. "In realistic terms it could be years, but I hope not. I'm really confident that it will happen sooner rather than later."
The couple have kept news of the March engagement quiet, choosing not to mark the moment with a traditional engagement ring, having already exchanged rings "years ago".
She told New Idea that Tony and Margie Abbott will "definitely be there" on the big day, while Ms Edwards told the magazine that "instead of bridesmaids, we're going to have drag queens".
A same-sex marriage bill is due to be voted on in the ACT on Tuesday, potentially paving the way for equal marriage rights across Australia.
On Monday, the ACT government revealed it would amend its marriage equality bill after legal advice that it was in danger of being defeated in the High Court.
The amendments change the wording of the bill so that it clearly identifies the laws as being for same-sex couples only.
Seven Christian, Islamic and Jewish leaders had earlier urged the ACT Legislative Assembly to defer a vote on the marriage equality bill, and send it to a committee for investigation.
But the government said on Monday the bill would still be debated on Tuesday and it is expected to pass that day.
Tasmania's same-sex marriage legislation was voted down last year. A new bill, due to be introduced last week, was delayed after a challenge from the Save Marriage Coalition on the grounds of being unconsitutional. Those concerns have since been addressed, said Australian Marriage Equality National Director, Rodney Croome.
Ms Forster says she wishes supporters of state and territory same sex bills every success, but that "the important thing is the federal act, that's what we need to get changed".