The development of a Cooperative Information System (CIS) becomes more and more complex, new challenges arise for managing this complexity. So, the aspect paradigm is regarded as a promising software development technique which can reduce the complexity and cost of developing large software systems. This opportunity can be used to develop a CIS able to support the interconnection of organizations information systems in order to ensure a common global service and to support the tempo of change in the business world that is increasing at an exponential level. We previously proposed an approach named AspeCiS (An Aspect-oriented Approach to Develop a Cooperative Information System) to develop a Cooperative Information System from existing Information Systems by using their artifacts such as existing requirements, and design. In this approach we have studied how to elicit CIS Requirements called Cooperative Requirements in AspeCiS. In this paper we propose a weaving process to define these requirements by reusing existing requirements and new aspectual requirements that we define to modify these requirements in order to be reused.