The objective of this paper is to describe the implication of an interdisciplinary team involved during a user-centered design methodology to design the platform (WebSoKeyTo) that meets the needs of therapists to design augmentative and alternative communication (AAC) aids for disabled users. We describe the processes of the design process and the role of the various actors (therapists and human computer researchers) in the various phases of the process. Finally, we analyze a satisfaction scale of the therapists on their participation in the codesign process. This study demonstrates the interest in extending the design actors to other therapists and caregivers (professional and family) in the daily life of people with disabilities.