Creates or updates a patient's demographic record in the CommonWell Master Patient Index (MPI) using a local patient identifier. The system automatically determines the appropriate action based on the Patient ID, Organization ID, and Assigning Authority provided — updating the record if the patient already exists, or creating a new one if no match is found. The Assigning Authority must be associated with the provided Organization ID; a mismatch between the two for an existing patient record will result in an error and no update will be applied.