Hi everyone- newbie here so this may seem like a simple question- but I have been searching all night on a tutorial on how to do this to no avail. 
I am editing a clip where my mouth grows very big and I slowly swallow another actress like a snake. I tried creating a null layer and pickwhiping the motion tracking on my footage to the position of the null layer, but the liquify effect does not follow my motion so I end up with a crazy looking forhead, neck, etc as I move around.
How do I make my mouth huge with the effect, then have it follow my motion as I move around?
Thank you so so so sooo much!
~Heather Eve