I sometimes do sci fi horror stuff where I'll have a monster try to grab or eat a person.  I parent the person figure to the monster part I need, such as the hand, or the head.  I do this often. 

The main trouble I have with this sometimes is if I already have a hair figure conformed to the person, such as V4 or M4, and then parent person to the monster, it causes a bug where the person will not move correctly with the monster.  It will act like it is frozen in place.

The solution is very simple, just delete the hair figure, then re-conform it person.

Good luck,