Hey all, so as the title suggests, I'm trying to find out how to alter hair that I have for my Skyrim. The problem is, I notice there are 3 files:
Hair01.nif
Hair01line.nif
Hair01.tri

Basically, Hair01 has a pair of horns that I want, so I plan to butcher the mesh, and throw the horns onto Hair02. I assume "hair01" and "hair01line" are similar to the two body types (light and heavy). Or something similar anyways.
I imagine I can figure out the hair line stuff, but the problem is with the .tri. I really have no experience messing with them.

Any and all help is appreciated.

The tri files I'm pretty sure are facegen related, I believe these have not been decoded, nor are any tools available for editing them. Currently most hair mods just use the same tri file for all their hairs. Hairlines are just that, hair lines, in terms of using them I think you can get away with not having it at all as it is classified as an "ExtraPart" to the "HeadPart".

I believe alternatively you might be able to make the horns their own mesh, and have the hair their own mesh, then add the horns to the hair's HeadPart as an extra part. When a HeadPart has an ExtraPart it is included with the original in the process.