How to maintain IBAN

Hello Friends - I need to update IBAN for the New Bank set up I am doing in FI12. Pls let me know if it should be maintained in FI12 and transported to PRD or directly to be maintained in FIBAN in PRD.

(2) We need to update IBAN for large numbers of Vendors in Master data. Previously, It was not maintained. Pls let me know how it should be maintained in one go.

Pls share the Best practices for the above.

Thanks