The main committee room in Canberra's Parliament House has been quietly booked out by an unnamed MP for an anti-gay marriage summit promoted by the World Congress of Families.
"It's disappointing that government members are bringing the World Congress of Families to Parliament," said Greens spokeswoman on gay and gender issues, Sarah Hanson Young.
It's understood the conference will repeat the speakers twice throughout the day and include Dr Allan Tapper from the Curtin Institute of Public Policy, WA who has in the past argued that divorce and separation are large contributors to the crime rate.
He'll be joined by anti-gay marriage campaigner Peter Westmore from the Catholic-group the National Civic Council, who links children growing up outside "stable families" to "juvenile crime, drug taking and mental issues".
One of the visiting chair-people of the day is expected to be New Zealand Family First head Bob McCroskie, who earlier this year handed in his celebrant licence in reaction to his country's passage of same-sex marriage laws.
The Prime Minister's office have not responded to BuzzFeed's request to know if Mr Abbott will attend any of the sessions.
It's not the first time 'National Marriage Day' has been held in Canberra, but next Wednesday's summit comes just days before the World Congress of Families' regional conference.