I'm sure this is going to end up being convoluted, but if anyone can help
with this I will be so ecstatic!

I have an excel file that contains business names (Business), a unique ID
that will be used later for generating a letter (LetterID), and a month
field that tracks what month a particular order took place (Month). There
are other fields, but these are the only ones I'm concerned with. I will be
using this excel file for a mail merge with a letter template that will
generate a letter for each of the businesses in the list. There will be an
entry in the spreadsheet for everytime a business placed an order, so if
Business XYZ placed 12 orders for the time period I'm dealing with, then
there will be 12 instances of "XYZ" in the Business column of the
spreadsheet...and the month column will contain either Mar, Apr, or May
depending on when the order was placed.

Here is the problem...I'm wanting to add a field to the spreadsheet called
"Filename" that will concatenate together the business name, the unique
letter ID used for them this letter, and the months that the letter will
include information for. So essentially the filename template would look
like this:

BusinessName_LetterID_Months06

where Months could be any combination of Mar, Apr, and/or May and the 06 is
just marking the year.

Now concatenating the first 2 things is no problem...but figuring out how to
determine whether the Months should be Mar, MarApr, MarMay, MarAprMay, Apr,
AprMay, or May is causing me to pull my hair out. It's easy enough if there
is only one entry for a business because then obviously the "Months" part of
the filename will simply be whatever value is in "Month"...but if there is
more then one entry for the business, how can I programmatically find out
which months need to be included in the filename?

I hope this makes sense...my brain seems to be turning to mush over this.

-Brian