Heads, hair, etc need other gas files updated. See my head tutorial at the bottom of the page. This situation is the opposite of that, you're adding existing heads to new characters, rather than new heads to existing characters, but the same lists apply.
If you don't, she's restricted to the original head in the base model, which apparently is only listed so you can swap back to it. They all work by swapping the partial mesh defined as "head", whether they're hairstyles or helmets (or both). DS2 added ornaments which can go anywhere, so it's possible to add extra hairpieces that way, too.
Heads, hair, etc need other gas files updated. See my head tutorial at the bottom of the page. This situation is the opposite of that, you're adding existing heads to new characters, rather than new heads to existing characters, but the same lists apply.
If you don't, she's restricted to the original head in the base model, which apparently is only listed so you can swap back to it. They all work by swapping the partial mesh defined as "head", whether they're hairstyles or helmets (or both). DS2 added ornaments which can go anywhere, so it's possible to add extra hairpieces that way, too.