Introduce new node "scenario.attributesPsychology" into JSON. Move "scenario.attributesSimulation.usePsychologyLayer" to this new node. This new node "scenario.attributesPsychology" holds also the newly introduced "AttributesPsychologyLayer" which is populated with default values when the migration assistant runs. The final JSON looks like this then: { "name" : "ScenarioName", ... "scenario" : { "attributesSimulation": { ... }, "attributesPsychology": { "usePsychologyLayer": true, "psychologyLayer": { "perception": "SimplePerceptionModel", "cognition": "CooperativeCognitionModel" } }, ... } }