Sometimes in blender, the objects become the child of each other, dont even I know why that happens.. happened to me a couple of times exporting body mods, well, in that case, I tend to export all the meshes separately into NIFs and then copy / paste branch into one NIF. Objects should be "NiTriShape" instead of "NiTriStrips", unde one NiNode or (BSFadeNode) NiTriStrips are used usually where texture animation is intended.