modify existing oldvalue and newvalue in CDPOS

Hello,

I need to go back through existing change records in CDPOS for one table and modify any oldvalue and newvalue fields that are there, for data security purposes (i.e. mask sensitive data).

I have seen that there are existing function modules for reading the change tables and adding new records to the tables, but are there any for modifying existing records?

Can anyone point me in the right direction here?

Thank you,

James