Dave was a bachelor who lived in Sydney. He was a loner and in ill health. He contacted his sister, Keren, in Oxford, England and asked her to move to Sydney to help look after him. He promised that if she did, that he'd leave all his property to her on his death. Keren agreed. She resigned from her job, sold her house and moved away from her friends. She arrived in Sydney and began to care for her brother. A few months later they had a falling out. Dave sold his property and disinherited his sister. His sister sued for breach of contract. Advise Keren and cite an example of relevant case law. (5