Are you entitled to claim half of her property in family court, if you were in de facto relationship more than 12 months? Or does this rule only apply in VIC?
Or at least you could threaten her that you will go after half in the court if she does not sign.
It's a commonly-thought, but incorrect, belief that by marrying someone (or being in a de facto relationship with them) that you will automatically get 50% of what they have when you separate. That may be the case for long marriages or long de facto relationships (depending on a number of factors), but it is not going to happen for ones which only last a few years.
FYI, to make an application in the Federal Magistrates Court in relation to de facto property settlement, you need to have been in a de facto relationship for 2 years or more, have a child of the de facto relationship or be able to argue that you have made 'substantial contributions' and it would be unfair if you weren't allowed to commence proceedings. It's a technical area - speak to a good family lawyer.