Hello Danielle, my name is*****
Firsty on the face of it you would have a claim. As you are not married you use the law of equity and trusts.
If you make a financial contribution you can claim a financial intetest.
As the assets is in Australia you would have to make an application there.
It would seem that the Australia operate the same principles as in the UK and in fact make it easier to make a claim as the test is not as high as it in the UK.
I have found the following from a website of a lawyer in Australia:
One of the more creative mechanisms for the imposition of a constructive trust has been in domestic relationships. This is because, unlike the other equities, the binding of the putative trustee's conscience is not necessarily based upon any wrong-doing or fault on their part. Rather, where there is a joint endeavour established by a domestic relationship over a period of time, a constructive trust is imposed where it would simply be unconscionable for one party to retain solely the benefit of the fruit of that joint endeavour. This is, of course, proved by the contributions made, both financially and non-financially, to the fruit of that joint endeavour. In addition, the Australian courts shied away from the English approach of trying to establish a "common intention" to form a trust and for good reason. One could easily imagine the evidential nightmare of trying to establish, through a combination of past words and deeds by the parties to a domestic relationship, such an intention.
The above being the case it looks promising. In the UK not only do you have to make a financial contribution you have to demonstrate there was a common intention for you to have a financial intention. However in Australia it seems that is not necessary the financial contribution alone seems sufficient.
It maybe that the application of the law may change from state to state in Australia, it is doubtful that is the case here.
In short though you would have to pursue a claim in Australia.
I hope this helps.