Okay, the robe I can understand in that regard; I wanted to make it easier to find everything when I made him his mod, so I made copies of all the .nif files I wanted to use and I renamed them, names like MyMod.NifCreatorName.RobeShinyBlueStars_gnd.nif, stuff like that, and moved them to the MyMod folder. In my render window they still looked exactly as they should so I figured it would work for him if I sent him the Meshes/MyMod folder but sent him a whole smattering of Textures folders with their original folder- and file-names; obviously I was wrong. How are the meshes and textures linked together? Would putting the files in Textures/MyMod and renaming them things like MyMod.NifCreatorName.RobeShinyBlueStars.dds make it work, or are they linked with a certain program that I don't have (anything that's not the CS or Oblivion itself)?
Yeah, the robe I can understand. It's the horses I don't get, because I went through his mod and changed all the stock Oblivion horses to .nifs from Zira and AlienSlof, and I sent those to him as well. No filename changes involved there. And he swears he put them where they're supposed to go, but all the horses in his game are just as invisible as the clothes and weapons and armor and furniture that I sent him.
They are linked with a program you don't have - Nifskope! Google it and download it, it's free. Once you have it installed, double-clicking a .nif file will open it in Nifskope so you can see the model and change many of its properties - including the texture paths for various pieces of it. So if you send your brother these files:
~Meshes\MyMod\MyRobe.nif
~Textures\MyMod\MyRobe.dds
~Textures\MyMod\MyRobe_n.dds
you need to make sure that the robe's texture path in nifskope says, precisely, "Textures\MyMod\MyRobe.dds". Start by expanding each branch till you see a little nightshade icon, that's where the texture path is. You can either right-click the path and choose a new one via explorer, or manually edit the path by double-clicking. Once you're sure you've got every texture path right, save the .nif file, and you're done!
It's important to note that because the game's default textures are packed in a .bsa file, Nifskope will show any areas where you've left a default texture as white (meaning missing texture), but it will still work in game. Best way to playtest it is to make your upload package, then move all your working files from your Oblivion install into a temp folder, and then copy from your upload package. This way you can be sure everything is there and working.