Oh, so you need a ready-made macro ... a forum is not the place for this .
Anyway, are the files all in one folder or even in subfolders ? so the path can be hard-coded in the macro.
Do the files contain a single sheet that has the right-footer to be update ? and does this sheet always have the same name ? elsewise you will have to loop through the sheets or skip some.
Does the actual right-footer contain a single data (old form number) or is it merged with other data ?
Do the files contain autorun macros ?

__________________
Difficult is not to know but to share what you know (Han Fei Tzu reworked)