The description of your problem seems very simple. But you're making it sound very confusing. so...
I have spent hours on trying to figure out how to import pre-made art files, but none show up. Is there any way to fix this?
Place them in the correct sub-folder in your Data Files.
You don't want the path to be too long, or you'll get a warning when you use the file in the CS.
You then select the correct file from the object's reference window in the CS.
If the file is a format that the CS can use, it should work.
They are the trees from sosltheim. I got them from a CD and added them to a mod of mine. I did not make new copies. They were the same exact ones as in sosltheim.
You don't need to pull files from the CD unless you want to modify the file itself.
If you want to just use trees from Solstheim, just get them in CS by activating the Bloodmoon.esp
I think that I made a plugin that was combined with the masters. It did not work. I opened up bloodmoon, and it did. I'm thinking of removing and re-combining files
There is nothing wrong with making an esp dependent on the three Masters. That's how the you use the resources from them.
If you're using these trees, you need to have Bloodmoon.esp activated alongside your mod.
Are you using a modified
Flora_tree_BM_01 file? If so, there's something wrong with it and you should delete it from your Data Files so that the game returns to using the original one. Morrowind will always use the default file if a modded one is not present.
Keep in mind that objects need
two files. A Mesh and a Texture. The problem you're describing is a missing Mesh.
Hopefully, I haven't read your posts wrong and misunderstood you. And I hope that my post helped