What this mod does:
This mod gives Lydia the head mesh and face tint from Chao's excellent mod.
She will use whatever body model and textures you have installed.
I personally recommend Fair Skin Complexion by HHaley.
It also replaces her hairstyle with the Only You 2 style (static) from the KS mod.
There is an SSE conversion of KS HDT Wigs if you want to give her the SMP version of that hair as a wig.
The KS mod is not required by this mod, but in the interest of saving storage space it does reference the models and textures
in the original location the mod would have installed them in, so allowing overwrites is safe if you have the KS mod installed.
This mod also turns off the opposite gender anims flag for Lydia.
There is an esp, form 44.
The head mesh has been optimized and then hand fixed in NIFskope by replacing the relevant parts in the original Lydia facegen mesh.
For some reason just optimizing the CK generated facegen mesh appeared to mess up some verts, but it ended up to be a skeleton issue.
The texture did not require optimizing.
I originally started this mod because every time I gave Lydia an SMP wig to use the vanilla hair still showed and I wanted to make it go away.
The only way I could get it to work was to change her hairstyle.

Chao's facegen uses the crystal blue eyes from eyes of beauty so I added that as a requirement.

Assets Used:
Chao's Lydia Replacer Lite Edition https://www.nexusmods.com/skyrim/mods/80190
KS Hairdos SSE https://www.nexusmods.com/skyrimspecialedition/mods/6817
Tools Used:
SSE Nif Optimizer
SSEdit
NIFskope
Bethesda Skyrim SE Creation Kit
BAE
7zip
Source Permissions:
Chao:
 "I will allow your request.
 You can remodel if you put the description of the change point.
 This sentence is a google translation because I can only speak Japanese."
KS Hairdos SSE 'You are free to use this mod for any follower and npc mods.'