Models of deliberative dialogue are fundamental for developing autonomous systems that support human practical reasoning. However, we must consider whether these existing models are able to capture the complexity and richness of natural deliberation for developing real applications. In real contexts, circumstances relevant to the decision can change rapidly. In this paper, we introduce an extension to today\u27s leading model of deliberation dialogue to capture dynamic changes of circumstances during dialogue. Moreover, in natural deliberation, a dialogue may be successful even if a decision on what to do has not been made. A set of criteria is proposed to address the problem of when to close o the practical reasoning phase of dialogue. We then discuss some initial efforts to introduce those characteristics within an existing model of deliberation for agent collaboration. We believe that our extended model of dialogue may represent that richness of natural deliberative dialogue that is yet to be addressed in existing models of agent deliberatio
