Zedahktur

Okay so, I've made custom models before by just adding or removing a mesh. And maybe edit the texture and UV map... But when it comes down to Cata models, they always attach themselves to a singular bone rather than the one I assigned it to. Like... Let's say I want to give a model a weird tendril coming out of his/her mouth or eyes. So I assign it to whatever bone# is in the head, but instead of following said bone it instead follows the chest or arm rather than the head. And this just repeats over and over with any bone I touch. Please help!