Prevent Credit exposure during release to accounting ( VF02 )

HI Experts,

Currently we have a requirement to prevent Credit exposure during SO, DN, and BL, we manage to do that, the problem now is when BL is released to accounting ( VF02 ) the credit exposure is accumulated, any idea which flag/field to set and which user exit ( We currently set the flag xkomv-kzwiw to space when it's 'A' ).

Thanks,

Gilbert