How do you combine Appearance.2da files so that they work together?

You have to know a little bit about this area in order to do it.

First you need to have a fresh Appearance.2da file open and I think that if you see anything after the row 510 or somewhere around that number at least for K1, and simply copy and past them into the file.

Copy and Past I'm not sure if you can do it from one file to another but you can manually type in the names and it should work.

Hope this solves your problem.

2DA mods aren't limited to new rows. Often they invole changes to existing rows.

You might want to look at converting any old mods that involve edited 2DAs to TSLPatcher. I do that for any such old mods I use to make them as compatible as possible.