How to add the tag 83D to the SWIFT MT300 format created by TSW1 ?

Hi.

I'd like to add the tag 83D to the SWIFT MT300 format file created by TSW1 to confirm the FX contracts.

The 83D means "Fund or Beneficiary Customer".

Could I do it by User exit , BADI , or SAP Form ?

Best Regards.

Yugo