This paper deals with a problematic not deeply studied as yet: user's goals interaction. A situation of multiple goals occurs as soon as the user utters a new goal whereas the previous one has not been solved yet. We propose an algorithm to identify the kind of multiple goals according to the task state and to the goals themselves. We define ten strategies to process those situations. Three meta-strategies order the strategies relevant for given situations. The system checks the preconditions of strategies to be sure they can be triggered. When a strategy is applied, the system updates the dialogue history and the task state. Some strategies push a goal in a stack and pop it when the first processed goal is fully reached.