Enhance MIRO tcode

Dear All,

I would like to enhance Amount Split subscreen (screen no 0090) in MIRO transaction. The column to be added is State Central bank Indicator(BSEG-LZBKZ) field in the Amount Split screen.

Could you please tell me which function module in function group FDCB updates BSEG table? So that i can update LZBKZ field in BSEG.

Is there any User exit or BADI for this enhancement?

How to proceed with this enhancement?

Thanks in advance