Process flexibility is an important issue in the business process management area: it has mainly been investigated in the context of intra-organisational processes but it received little attention in the context of processes crossing the boundaries of companies. This paper addresses the issue of BPMN collaborations and choreographies flexibility, advocating a version-based approach. Indeed versions, which have been recognised as a powerful mechanism to face flexibility of internal processes of companies, are used to address flexibility of processes crossing the boundaries of companies, modelled as collaborations or choreographies in BPMN. Thus this paper extends BPMN collaborations using versions. It also introduces algorithms supporting the mapping from versions of collaborations into versions of choreographies. This paper mainly focuses on static aspects of collaboration and choreography versioning.