Ornatrix depends on the distribution mesh to generate roots and interpolate hair. If the distribution mesh changes, the hair will change as well. You can deform the mesh moving vertices and polygons, but you should not modify the topology. This behavior is expected.
I know is a bit frustrating if you don't have this information from the start. Even if you don't change the scalp area and just add polygons to the hears of face, Cinema will recalculate the whole mesh and Ornatrix will read the updated data. A workaround to this is to use the Re-Target Changes (docs here )or Remember Roots Positions (docs here) option. Find information about those features here. Let me know if you have questions about them.
