Problem joining mesh with hair

Hi all,
I was modeling a character, starting with his head, and made some tests giving him some hair. I was moderately satisfied with it, but I decided to go on modeling the body and tweaking the hair later, so I separated the neck vertex into a new object, extruded and started modeling the body. But when I was happy with it and joined it (CTRL+J) back into the head mesh, the hair got all deformed and mangled up…
It’s no big loss if I have to restart grooming the hair, for it was not the definitive thing, but since I had some already made, I wonder if there’s a way of joining the meshes without screwing the strands.
Thank you. :slight_smile: