In a worksheet called "amex summary.xls" I have several cells that reference
external files to retrieve data from cells within those worksheets. One of
the Summary sheet cells reads as follows:
='[amex charge_constance lundy.xls]summary'!$D$3
It pulls values from one file into a summary file. Within the summary file
there are about 110 entries for each individual outside file.

Is there a way to make one cell in the summary worksheet reference the
outside file name and then have the 70 entries for that sheet look to that
cell for the filename and concatenate the filename with a particular cell
reference?

The reason for this is if a new person needs to be added to the "amex
summary.xls" file I first copy and paste one of the existing cell groups and
then have to go in and edit 110 separate line items so they now reference the
new file name.
Each month employees receive bills from their amex card and submit an
expense sheet electronically. I then summarize all the info via the "amex
summary.xls" file and use the summary data to post to our accounting system
instead of having to go in and read each individual file.