I added some custom hairs from a resource I found on the forums here to DK race I downloaded from nexus. Now all is great and works fine except for when I put a hat or helmet on - the hair mesh doesn't change at all and it pops out of helmets and/or hats. Or worse, when I put a ranger hat on it appears as if I don't have hair at all.

Now I remember that I used to make custom hairs behave same as Wendy the Welder hairstyle when using head gear. They appeared as a shorter mesh of that hairstyle...but now I can't remember how I did it for the life of me. Does anyone else know and can help me with it?

Hair meshes need 2 primary NiTriShapes, named in a specific manner - Hat and NoHat. NoHat is the hair that you see without any helmet/etc on, and Hat is for when you're wearing something that replaces the hair (cap, helmet, etc).

Your best bet is to make a custom Hat NoTriShape, so that you can take your custom hair and reshape it to suit the needs of whatever helmets/hats etc you intend to use.

Awesome, thanks Vixen. I didn't even think of NifSkope, completely forgot what I was doing the last time. It was 2 or 3 years ago after all.