In my understanding there is no way to directly edit a mesh that is in a trainzmesh format. If it is in fbx then you can import into blender. If not, the only way to edit would be to add an attachment with attachment maker and then you could add meshes. You could “delete” parts of the original mesh by making their texture disappear with the alpha layer. Needless to say, this isn’t very elegant and becomes a bit hopeless if you need to make big changes. Just reskinning doesn’t require changing the mesh, just editing the textures, If you describe what you need to do, that might help.
