Need a BAPI to modify sales document (Inquiry) header conditions

I need a bapi to modify header conditions on an Inquiry sales document. BAPI_CUSTOMERINQUIRY_CHANGE has the appropriate condition and conditionx tables. However, according to the documentation: "Although the BAPI interface is supplied for the condition to be changed, the system does not return the required result and/or the pricing result is inconsistent. Currently, the change of condition lines in existing documents via the BAPIs provided by SAP is not implemented."

Thanks

Leo