f-58 enhancement!

Dear Experts!

My requirement is to change the vendor reckon account no. (i.e.associated with the vendor code) at the time of document posting @ f-58 / fb60 transaction.

At the time of document posting this reckon acount no. of the evndor is automatically picked up from the vendor master but here the requirement is to change this reckon account no. with the other one at the time of posting the document.

Could you please suggest me the appropriate badi or exit to achieve this requirement.

Thanks in advance,

Baig.