Joint remote state preparation

Alice, Bob and Charlie are three remote parties. Alice and Bob share the classical knowledge of a secret qubit state. We consider the following question: 'how can Alice and Bob jointly prepare the qubit state for Charlie?' Two different protocols are proposed for such a joint remote state preparation. The first protocol uses a single GHZ state while the second one uses a pair of EPR states as the quantum channel whose entanglement is not necessarily maximal.