Base Line date automatic capture from Document Date

Dear All,

Please help me on that issue.

i) At the time of MIRO, Base Line Date are automatic capture from the Posting Date, but our requirement is it should be capture from Document Date.

ii) I have create a new Payment Term (Tcode : OBB8) with maintained the Posting Date option under "Default value of Baseline Date".

But, at the time of MIRO, when we change the Base Line date then system automatic change the "Due on date"

with Regards,

Uttam Maity