Help: Error with Nifmerge

[DovahKya]

Hello there!

I have a strange problem with nifmerge, I've tryed to search my problem on internet but can't found nothing, hope you can help me.

I've decided to create a male follower inspired by an anime character, so I used SAM body and bochu race (So I can use female head mesh). I've created the preset and exported the head like always. I've created the follower, merged the head with the facegeom using nifmerge and it perfectly works, at this point I've decided to try to put HDT hair on him. 

The hair more like what I needed where from Yundao HDT hair, this mod adds just wigs and not hair for the racemenu (so they don't have hair and hairline but just a unique nif file), so I opend the nif file, Iv'e duplicated it and I've deleted Hair model on the first and harlines on the second. I've created a separate mod just for them, setted as unisex, I've tested it in game and they perfectly works  on male and female and on every human race, even bochu, and the HDT also works well.

Spoiler

So I've re-made the preset and I've re-exported the head, I've changed the mesh of my follower and I've generated again the facegeom and I've tryed to merge it again with the head, and I've got this:

Now I'm stuck and I don't know how to go on, I'f I can't fix this I guess I'll must use the static hair, but I would understand what I've did wrong.

Yundao_HDT hair V5.5 (I've used 170kshair)
https://www.nexusmods.com/skyrim/mods/88416

I love to experiment and to learn, but sometimes I'm unable to figure it out what I did wrong. Hope I gave all the information that it needs.

[DovahKya]

Mhh ok I think the problem depends on the skeleton but Idk how to fix it, I tried with SAM skeleton, vanilla skeleton and XP32 skeleton but nothing change, For now I'm using the hair as a wig.