Thanks guys, I'm going to try some of these solutions right now!
The file layout order matters, but not the record order; meaning the end product could be:
aaa|bbb|ccc|123;456;789|ddd
abc|def|ghi|123;456;789|jkm
or
abc|def|ghi|123;456;789|jkm
aaa|bbb|ccc|123;456;789|ddd
...and the "pay grade" things is just a joke. It means that this type of coding is out of my league (i.e. I'm just a low level coder).