In our past work, we presented a framework for the decentralized control of discrete event systems involving inferencing over ambiguities about the system state of various local decision-makers, and introduced the notion of N-inference-observability as an existence condition of a certain decentralized supervisor. When a given specification fails to satisfy the N-inference-observability property, a supervisor achieving the given specification does not exist, and a technique for synthesizing a decentralized supervisor that achieves an N-inference-observable superlanguage is presented here (a dual problem of computing an N-inference-observable sublanguage was studied in our past work).