From my understanding, the structure of transferring property, while different in each state, we do share some things, which we inherited as we operate under the westminister system. The reason, that buyers insure, is effectively, they are contracting to buy land, which is very accurately described, and then there is simple reference to their being a building on the land. The reason a buyer is asked to insure, is that they are considered to have an equitable interest in the land, via the contract. I do believe that the seller does not have to warrant the adequacy or otherwise of their insurance cover from sale to settlement, and a buyer can only withdraw, if an event occurs and the property is no longer habitable. That expressions is quite wide, and hence room for a lot of arguement. In this situation, I would see if the sellers claim on their insurance is successful first, and then revert to my policy. I do not like to have claims on my policies where I can.