[{"basicData":{"owners":[{"relatedJson":{"basicData":{"devices":[{"equipmentID":"abcd","type":"camera"}],"otherFieldsBasicData":"other values","evenMoreFieldsBasicData":"other values"},"otherFieldsRelatedJson":"other values","evenMoreFieldsRelatedJson":"other values"}}]}}]

db.collection.update({"basicData.owners.relatedJson.basicData.devices.equipmentID":{$exists:true}},[{$set:{"basicData.owners":{$map:{input:"$basicData.owners",in:{$mergeObjects:["$$this",{"relatedJson":{$mergeObjects:["$$this.relatedJson",{"basicData":{$mergeObjects:["$$this.relatedJson.basicData",{"devices":{$map:{input:"$$this.relatedJson.basicData.devices",in:{$mergeObjects:["$$this",{equipmentId:"$$this.equipmentID",}]}}}}]}}]}}]}}}}},{$unset:"basicData.owners.relatedJson.basicData.devices.equipmentID"}])