Multiple spreadsheets are updated by multiple users. Users should not add, delete or change data that affects totals after a set deadline. Not all users are respecting the deadline rule. The totals from each spreadsheet are linked to a master spreadsheet. When I update links on the master, I would like the cells that change value to turn a color or some other identifier. Locking down the multiple sheets at time of deadline is not practical due to the volume of files. An alert, such as color, would seem to be a reasonable solution. An example would be:

Master spreadsheet contains a linked total (time) - 8:00:00
User inputs data in source doc and increases time - 8:15:00
Master spreadsheet - edit link, update - results in - 8:15:00

All of that is correct, except that it occurred after a deadline. Can the updated cell turn to a color?
I need the time saving feature of knowing the change has occurred. I will then be able to identify the user through file properties.

Thank you,
Miss M