Understanding add_to_order_flag functionality for service requests

Hi,We re submitting orders to Order management from Charges screen of Service Request. Our expectation is to create a new order number for each submit but it is adding lines to the first created order. I read about the add_to_order_flag, and i expected to create new orders when it is N. But during my tests, new order was not created even if this flag was set to N. Then I checked CS_CHARGE_CREATE_ORDER_PVT.SUBMIT_ORDER api, apparently when i set this flag to F; it creats new orders. I cannot see any field in the screen to change this flag to I updated