Inserting (Creating) Parent - Child record in Siebel via SOAP Inbound Webservices (Opportunity - Opp

Hi Gurus,

I am trying to Inserting an Opportunity (Parent) and Opportunity Attachment (child) in the same SOAP message as an INbound to Siebel CRM.

I am passing the SOAP message (in SoapUI for testing) where I am supplying all the required fields as per the IO and BC ..

The Opportunity record is created (Parent) and the ROW_ID for S_OPTY is also generated, but the SOAP message fails with the following error on the child IC (Opportunity Attachment)

SBL-DAT-00498: 'Oppty Id' is a required field.  Please enter a value for the field.

ObjMgrLog Error 1 0000007e5a1e1864:0 2017-11-29 07:54:29 (adptutils.cpp (7082)) SBL-EAI-04389: Required field is missing in instance of Integration Component 'Opportunity Attachment' with the user key '[OpptyFileExt] = "txt" AND [OpptyFileName] = "NVTESTUpload1"':  'Oppty Id' is a required field.  Please enter a value for the field.(SBL-DAT-00498)