27. For each case where a town planner is entrusted, by different clients, with interrelated mandates or concerning the same territory or part of territory, he shall inform each client of the subject and the duration of the mandates entrusted to him by the other clients and obtain their consent to the carrying out of the mandates.
The agreement does not exempt a town planner from the obligation to not prefer his own interests over those of a client or the interests of one client over those of another client.