It has been a while since I did Cobol but you can do this by renaming the record format to on of the files. I don’t remember the command but redefine sounds right.
A COBOL program has no problem opening both a physical file and any or all of its associated logical files. There is no need to rename formats. (I’m not aware of any facility for renaming formats in COBOL, though memory areas may be ‘redefined’ with additional names. Also, COPY statements may replace text with other text.)