I have some long beards I have imported into CC3 and used the weight transfer tool to convert them to hair.  
Overall works well and follows the jaw and mouth pretty good.
Problem is with the long beards .the lower part of the beard attaches to the neck.  So when rotating the head, you get an odd. Looking stretch of the lower portion of the beard.

Is there a way to detach certain portions of an object from the weight mapping?

Thanks. LarryJ