Do the dolls with "naturally curly" hair retain their curls after it gets wet? Or should this only be done to straight hair dolls?

(Not steaming, or downy, but soaking with water)

I tried to work on Felicity's hair, but I noticed one of the threads that sews the hair down is broken and it kind of spooked me. The hair is attached to the wig through the wig also, right? Not just sewn on with that one exposed thread? Or should I not brush her hair anymore, for fear of loosing that entire row?