Animation help - lattice within a lattice?

[ponyo42]

I have a simple cactus character I need to animate. As it doesn't need any lip-synch, just to be able to smile/frown I was planning on putting a lattice deformer over the mouth shape to be able to pull up the ends or push them down as needed. However, I also need the charter to be able to lean gently from side to side and back and forth - which I had also planned on using a lattice for. 

Is the lattice over the entire charter going to mess up the lattice over the mouth, or should this be fine as long as the body lattice doesn't get too extreme  in its movements? 

Thanks in advance!