Traditionally, research in support for collaborative document edition has concentrated on non-monolithic edition, i.e. edition processes in which parties are unitary decision entities cooperating inside a single group. In this paper, a model for non-monolithic collaborative document model is introduced. This model, named the document-group-message model and being a work-in-progress, integrates a multiversion document model, and support for group dynamics and message exchange. Design of support systems for non-monolithic collaborative document edition based on the document-group-message model is also presented in this paper.