Protect Original Data From Changes

I have a tracking log, stored on a network drive, that tracks open purchase orders on about 13 different buyers. Each buyer has access to this data, and would be interested in looking at it in different ways. I have an idea for protecting my original data in this workbook, but allowing others to view and edit the data anyway they want. I thought I'd run it past the pros first, to see if they knew a better way, before I started trying to code it.

My idea was to put a macro in the workbook open event that opens an input box, "Enter password or select okay." If they enter the correct password, the macro exits, and they are in the workbook. Any changes made after entering the correct password will be made to the original data. If they enter anything OTHER than the correct password, the code would save the workbook AS another name, so now any changes made would be only made to a COPY of the original data.

This way, when I do my daily updates, I can open the file using the password, and save the file after editing. Anybody else would only get to edit a copy of my original. The other question is..., is it possible to put a macro in the workbook exit event that requires a password to overwrite the original? Otherwise, the user could edit the data in the "saved as" version, then just overwrite the original file, either accidentally or maliciously. I know they could still overwrite it by editing the macro, but I don't think they're that savvy.