Prime Minister Tony Abbott's sister Christine Forster is determined to marry her fiancee Virginia Edwards in Australia, but concedes she likely faces a ''long engagement''.
Sporting a rainbow tie-dye T-shirt and with her partner by her side, Ms Forster marched with fellow Liberal Party politicians in the Pride March on Sunday.
About 30,000 people braved near-40-degree heat to watch the march on Fitzroy Street, St Kilda.
Ms Forster, a Liberal City of Sydney councillor, said the march was a ''wonderful celebration of community, diversity and equality''.
She said Australia's laws preventing same-sex marriage were ''the last bastion of inequality for gay and lesbian couples''.
Ms Forster said she and Ms Edwards had agreed to only get married in Australia.
''It's not a pressing need for everyone, but for same-sex couples wanting to get married it is extraordinarily pressing,'' she said.
She said marriage equality was now ''open for discussion'' within the Liberal Party. ''That's a big shift in my mind.''
Pride March Victoria president Matt Renwick said the march was a celebration.
''We are a strong and dynamic community - there is something for everyone,'' he said.
''We are here and we are proud.''