mass changes in bank account in bp

Hi experts!

I need mass update in field BANKN and BANKL. In the moment I use t-code BP and make the changes one per one, but I need to modify in mass (at least, 500 or more BP's).

I try to use t-code MASS, but I don't find the object.

Could you provide me help?, please.

Thanks in advance, best regards,

Alejandra.