The following code sample enables you to split an existing valid order into multiple orders using OrderId and OrderLineNumbers.

Sample snippet:

// split the order
    Apttus_Config2.CPQStruct.SplitOrderRequestDO request = new Apttus_Config2.CPQStruct.SplitOrderRequestDO();
    request.OrderId = 'a2n7A0000002jnWQAQ'; // order id to create split order from
   
    request.OrderLineNumbers = new List<Integer>{1}; //add order line numbers to be part of new split order
   
    Apttus_Config2.CPQStruct.SplitOrderResponseDO result = Apttus_Config2.OrderWebService.splitOrder(request);
       
    Apttus_Config2__Order__c splitOrderSO = result.SplitOrderSO;