Why not let that person have a limited access to your application and get then to enter the data directly? Access is a multi user capable db...
failing that make certain you have the primary key for each row embedded in your excel sheet, so that when the data comes back to you you can identify the row(s) in the table to be updated
if this is a regular process then If I were you I'd write a fully formatted spreadsheet , locking down clls that cannot be updated (so the user cannot inadvertently tinker with the spreadsheet. its virtually impossible to stop deliberate tinkering with a spreadshet, can you stop someone remvong the locking,m tinkering with the db ten re locking, but thats a different story
then write a VBA process which reads the data in from a spreadsheet and updats your db. but take adequate precautions against data corrupion., in my books its rarely smart to let users modify data in a spreadhseet that is to go back into a db, becuase its too easy to change stuff without realising or appreciating the consequences.
as part of your import process build in validation checks, decide how you want to handle errors. there's two choices,. either reject all changes untill no errors, or accpet what you can (and say put the errors in to a temporary location within the DB, until the user clears the errors. not onlky shoudl your import process validate on entry, but check that 'stuff' is where it should be (ie check column & row headings, embedd a version nuimber inside your spreadsheet.
if ytou dont' want to go down the route of writign a spreadsheet, and merely do an export to xls, then embed NOT just the priamry key for ewach roiw, but also some form of check digit validation on the PK, so if the PK gets changed you can identify it. Natch dont' let your users know what your check digit calculation is in case someone decides to maliciously modify something.
if you do automate the process document it well/extensively nto just for when you leave bu when you have to pick out the errors at daft o'clock at night under a time pressure. validate, validate, and validate before doing anything.
if you have a choice deploy an Access form and given them direct access tot he data within the DB. If you want to you can deploy a specific form within a front end which only allows the users specific access.
I'd rather be riding on the Tiger 800 or the Norton