There are 2 Alternative ways to own Property in Australia: Joint Tenants v Tenants in Common
In a Joint Tenancy all of the owners own the entire property. If one of them dies, the survivor(s) remain the owner of the property – it does not matter what any Will might say, until there is only 1 registered owner.

In a Tenancy in Common, each owner has a defined share – 50%, 30% etc. If an owner dies then their share in the property passes accordingly to the terms of their Will, or if they do not have a Will, according to the rules about intestacy.