Everyone here was tremendously helpful on a similar question a few weeks ago.
I'm really hoping I can impose on you one more time:

At the top of each year, we receive a "Master List" of projects with columns
A-L of data: Column A is the unique part number, while columns B-L provide
details. Every week, Corporate sends out updates, which may include either A)
new info for existing part numbers (meaning SOMETHING, who knows what, has
changed in columns B-L, though a part number already exists somewhere in the
Master List in Column A), or B) a totally NEW part number is being added to
the Master List, so that both the number in Column A AND all of the info in
Columns B-L needs to be added to the Master List.

I guess what I'm looking for is some sort of macro that I can run. I'm
imagining something like this: Corporate sends the weekly update workbook, I
drag the sheet from it into my existing Master List workbook, and then run
the macro. Based on data in Column A, the macro looks for existing part
numbers, and then, finding them, updates B-L accordingly, or, not finding a
number, just adds it on to the bottom of the Master List.

Frankly, I'm pretty sure all of this could be done more easily in a shared
Access (or even FileMaker) database--but well, I'm just a thrall in the mines
and I don't have those tools available to me.

I know this is asking a lot--but can anyone help? Probably some sort of XL
Guru could charge a lot for the sort of guidance I'm looking for, but
meanwhile, I'm kind of stuck, without a clue, and spending a whole lot of
time ever weekupdating this "Office Space"-like Master List whose ultimate
point kind of eludes me.