Looking for help for a sub to do this: Stack up identical structure data from
4 source files, then paste unique lines (based on "order id" col) into a new
sheet

I would run this sub from Personal.xls,
navigate to a folder, where there would be 4 files:
1.xls
2.xls
3.xls
4.xls

Each file contains only 1 sheet with data (sheetnames may vary from day to
day and are to be disregarded). The data in all 4 files are identical in
structure, with col headers in row 1, data from row2 down. Col B is used to
determine data extent.

The sub will create a new book, name it as simply: 1234.xls, save it into
the same folder as the source files, then copy n paste (stack up) entire data
rows from each of the 4 source files into Sheet1 (with col headers pasted
into row 1)

Then the sub will carve out uniques based on the "Order ID" col header, and
paste these unique lines into a new sheet, naming this new sheet as:
UniqueOrderIDs