Map<String, Object> nsCustomerSub1 = new Map<String, Object>();
nsCustomerSub1.put('entity', new Map<String, Object>{'internalId'=>'362'});
nsCustomerSub1.put('subsidiary', new Map<String, Object>{'internalId'=>'9'});
Map<String, Object> nsCustomerSub2 = new Map<String, Object>();
nsCustomerSub2.put('entity', new Map<String, Object>{'internalId'=>'392'});
nsCustomerSub2.put('subsidiary', new Map<String, Object>{'internalId'=>'9'});
// Initializing the RequestJSON Data to be passed.
Map<String, Object> requestJSONMap = new Map<String, Object>();
requestJSONMap.put('customerSubsidiaryRelationships', new List<Object>{nsCustomerSub1, nsCustomerSub2});
String reqJSON = JSON.serialize(requestJSONMap);
Map<String, Object> reqObj = new Map<String, Object>();
reqObj.put('version', '1.0');
reqObj.put('action', 'createCustomerSubsidiaryRelationship');
reqObj.put('requestJSON', reqJSON);
// Placing a request to Breadwinner Global API
Map<String, Object> resp = breadwinner_ns.BreadwinnerNetSuiteAPI.call(reqObj);
System.debug(resp);