There are many decision support systems to aid decision making in structured domains. Such domains are characterised by involving repetitive and routine tasks. They involve definite procedures for supporting decision making. Far fewer tools are available for reasoning in discretionary domains. Nevertheless, most management decision making is indeed unstructured -- the decision maker must provide judgement, evaluation and insights into the problem definition. In this paper we focus upon decision making in a discretionary domain -- namely how Australian judges distribute marital property upon divorce. Our system, Split Up provides such advice. The system has been developed in the object oriented expert system tool KnowledgePro.