Hi Hari,
For SAP FI Integration - please look at the following BADIs:
ES_DCFL_CUSTOMER_FIELDS_TV
BADI_DCFL_FIN_IDOC_DATA_TV
BADI_DCFL_FIN_SGTXT_TV
BADI_DCFL_FIN_PREP_TV
I have customized or extended the Standard Idoc interface using these BADIs.
Hope this helps
Thanks.
Best regards,
BG.