Contract Start Date and End Date in Sales order Maintenance Item

Hi Friends

I am creating Sales order and Maintenance contract using IDOC_INPUT_ORDERS and updating configuration values SD_SALESDOCUMENT_CHANGE.

if the IDOC comes with maintenance items we are creating Contracts.In this case, I can able to update contract start date and End date via function module. But in some cases I am getting regular and maintenance item via same IDOC. So we are creating OR orders with both the line items.

if OR order comes with maintenance item, I want to update contract start date and end date, But I am not able to change that via function module SD_SALESDOCUMENT_CHANGE. is there a way to update contract start date and End date.

Thanks

Gowrishankar