Identifying and representing domain requirements among products in a product family are crucial activities for a successful software reuse. The domain requirements should be not only identified based on the business goal, which drives marketing plan, product plan, and differences among products, but also represented as familiar notations in order to support developing a particular product in the product family. Thus, our proposal is to identify the domain requirements through goals and scenarios, and represent them as variable use cases for a product family. Especially, for identification of the domain requirements, we propose four abstraction levels of requirements in a product family, and goal and scenario modeling. For representation of them, variable use case model is suggested, and also the use case transfer rules are proposed so as to bridge the gap between the identification and representation activity. The paper illustrates the application of the approach within a supporting tool using the HIS (Home Integration System) example.