In order to choose the proper size of an infrastructure and to save as much as possible on investment costs, it is necessary for the responsible party (the Centre in the language of this report) to have access to information that is typically known only by some agents or partners who may use their privileged information in a strategic way. These problems are endemic to all societies, alliances, partnerships and public or private businesses. We consider in this report three specific but important contexts. In the first one, a business or alliance with several divisions or partners want to set up a common cost sharing method that induces the division managers or partners to contribute to the minimisation or at least the reduction of the common costs. In the second and third cases, the sharing of common costs appears in contexts where the division managers are the only ones informed of crucial elements for the determination of the firm's optimal program of activities. It must then induce the divisions or partners to reveal their privileged information. In spite of the significant difficulties in analysing those problems, the methodological approach that we propose leads to solutions that are often imperfect but transparent and informative.