You can achieve the same as a BFA, without the $5k price tag by lodging consent orders with the Court.
The only point you need to be aware of, is that the Court will review the orders and assess whether they are "fair and equitable"... and what you are proposing might not qualify...
This will achieve the same outcome, as the BFA, with regard to stamp duty, etc.
Here is a link to an information pack from the Family Court on consent orders:
Let me know if you need any further assistance, or need me to walk you through the process.
It is possible to do a Deed of Gift, it would be less paperwork, but stamp duty will apply... and it will not finalise financial arrangements between you both... and this is not ideal.
I can also assist with legal services, when it is time to transfer the interest in the Property, and register it at the Titles Office.