As it has been shown in several studies, work in a collaborative manner leads to a better achievement of the goals. There is a large number and variety of processes to achieve a certain goal; however, a lot of these processes have been designed to be carried out in individual work environments. For that reason, in the area of Collaboration Engineering it has been proposed a Methodology for the Development of Collaborative Processes, which allows obtaining the collaborative specification of a process. This methodology provides the Facilitation Process Model to represent the process flow, however, it has been identified the need to complement this model with elements that contribute to the understanding and future use. Thus, this paper presents a formal notation for modeling collaborative process extending HAMSTERS (Human-centered Assessment and Modeling to Support Task Engineering for Resilient Systems) notation, in order to complement the graphical representation of the model.