This is a general question about mods.

I like to run several different ones at once. If different mods have appearance.2da files, do they overwrite each other when you add to the override folder. which, in turn, would cause another mod not to work because the .2da file has been overwritten?

I like to run several different ones at once. If different mods have appearance.2da files, do they overwrite each other when you add to the override folder. which, in turn, would cause another mod not to work because the .2da file has been overwritten?

Yes, if you want to use multiple mods that all modify the appearance.2da file you will have to merge the file by hand, unless the mods come with a mod installer that does the work for you automatically. Missing 2DA references may cause the game to crash if you overwrite the file from one mod with the one from another.

You'll have to figure out which lines have been modified or added, apply the changes to existing rows to your appearance.2da file in the override folder, and copy&paste any new lines to it. If those lines are for player appearances you will need to modify portraits.2da to refer to the correct line numbers in appearance.2da you pasted the new lines as. If they are used by NPCs you will need to update the Appearance_Type field in their .UTC files to point to the correct line number.

Also keep in mind that if multiple mods come with a heads.2da file you will need to merge those as well, and update the normalhead and/or backuphead columns for their corresponding lines in appearance.2da to point to the correct line numbers.

Basically any 2DA files need to be merged, and any references to new lines in 2DA, GFF and NCS files updated to point to the line number the new lines end up as when you paste them into an already modded file.