The_Doc_Man: The survey databases do not use an autonumber field, I already thought of the possible problems with that
The survey consists out of 2 parts. They have to fill in a part for the site itself. This should only be done once, and therefore I have designed the form so that they can only enter one record.
After that, they need to fill in the details for every user. On this form, they need to select their site from a dropdown box which looks at the other part of the survey. This box should only have one option.
As a unique identifier, I have programatically created a key consisting out of the site-code and their full name. This is done out of their sight. (I would have chosen to use their email address, but in some African countries they only have 1 email address for the entire office - the problems of working for a truly global company I'd say

)
On top of all that, I have created a double check on the main form, which checks to see whether there is only 1 site entered, and whether the total number of users they entered matches with the total number of users that was entered with in the site part of the survey.
The users should only send back one copy of the survey (and only after they get the message finished on the main form), and since we have a list of contactpeople (1 per site), we will only accept the copy they send back. They would need to include a screenshot of this "finished" message with the email or the submission will be rejected.
Now to begin with, we only have 1 copy of the survey that is to be sent out. This copy will be downloadable from our intranet via a password protection. This way we can also see whether they have downloaded the survey to begin with.
I was thinking of placing the completed surveys all in subdirectories, where the directory name is the code for the site of the survey. This way, all "source" databases would have the same name.
Now offcourse placing these files in the correct directories is a terrible task to do, but thank god for students during the holiday period

Now would the solution you propose still work in the scenario of these subdirectories?
Furthermore, the survey database has already been tested by around 10 people from the office here (most of them know absolutely nothing about access etc. - to make sure that I could trap any errors). This especially done in mind of Murphy's law. I still remember surveys that were sent out (not prepared by me) and caused complete distasters. Needless to say that I will do everything I can to prevent this from happening
Do you have any other ideas of what I should do to prevent this survey from becoming my worst nightmare? If so, they would be highly appreciated.
Thanks.