I created and store in SharePoint 2 Excel files. File 1 contains all address records for an organization. File 2 contains, via VLOOKUP from File 1, a limited amount of the address records for the same organization (because it is viewed by a wider audience and needs to be a bit more restrictive). I gave the client access to both files and they update address information in File 1 regularly.
To have any address updates transfer to File 2, does the client need to have both files open at the same time when making address updates, so that File 2 is up-to-date?
You write that the client is updating records in File 1, which I'm taking to mean, making changes to existing records, as opposed to adding new records. If that's a correct interpretation, then they (or somebody else) should get a message when opening File 2, that looks like this:
They just need to answer "Update" and the VLOOKUP formulas in File 2 will get the updated information from File 1.
If in fact they're adding altogether new address records then you might need to change the range of the cells in File 2 to make sure that range is large enough to accommodate the new data.
P.S. I am speaking from experience with Excel. Never used SharePoint though, so if it introduces some different processes, what I have written might not be complete.