Modify Multiple Spreadsheets At Once

i have admit forms for multiple patients, about 200 or so already done, and its set up to make an upload sheet, which we then add all of them to one big file to import to access. i am in the process of cleaning things up, but we need to add a formula to a cell to determine length of stay, and several similar things, but i'd like to not have to go and do it file by file.

is there any way to update all the files at once? some kind of automation? then changes would be in the same cell for each file.

or maybe some way to do a batch modify or something, so it can make the change, and run the two macros, one to make upload for file, one to dump it in the file that goes into access.