What Hel borne said. 2nd'ed.
Then head will disappear when you wear the helm. Well, if it suppose to cover the whole head(without showing anything), it doesn't atter.
It will matter.
the helmet, in this case was probably not modelled so that the head really fits inside the helmet.- it was designed so that it covers the whole head, and uses both the hair and head slots. at least cultbrains original mod did/does.
the egms from the conformulator will not alter the helmet so as the helmet fits around the head no matter what. what it will do is morph the helmets shape slightly, totally in relation to the facegen parameters that is on that particular head. if the helmet doesn't really fit the head mesh in the first place, it'll still clip. and even then you have to line you geometry up with the geometry on the vanilla head to get best results, and/or give it a little room for error.
the helmet is rigged. therefore egms will be of no use according to scanti.
rendering the head underneath the helmet is just wasting resources.
Creating an egm probably takes longer, is more prone to not be the total fix ie fat heads and beasts, and will take testing, rather than opening the esp/esm in the cs and and ticking the head slot in the helmet entry.
the conformulator is obviously causing the op confusion.