UV Mapping in blender?

[Soulslayerzx]

Not sure if anyone knows how to uv map properly in blender, but I was editing a helmet. The uv map looks like the one extracted from the bsa, but if I hit u>unwrap, then it looks different. On this helmet, I removed one of the horns, patched it in, the whole helmet looks fine with the extracted texture except with the patched up part and some other parts I added. So which uv map do I use?