The email before was too long About the same: ============= - commercial_id is not required on all objects as it's exactly the same than partner_id.commercial_id, so we will just put it where it's required as a technical artifact to allow specific reporting, not everywhere. ============= Case 3: Mix of Case 1 and 1: We can have case 1 and 2 in my last comment mixed. (You are migrating now one db with this approach A***) A "consortium" of companies with several childs that have "Subsidiaries" and with sevaral "Locations". IT is so much complex, we mix all our modules and we are improving all the interaction between the to solve this (It is a WiP) but I am aware that with all the restrictions an python code involved in Odony Solution without touch the db, it will become in a real mess. But BTW, I am open to hear solutions? Thanks 2013/4/15 Fabien (Open ERP)