Splatting in Blender

I followed some tutorials to figure out splatting textures in Blender, but all of them handled just two texture passes. Supposedly you can have more using multiple stencils. But when I organize my texture layers like so:

grass
stencil1
dirt
stencil2
snow

I can only paint snow over dirt textures. What if I want to paint it across grass -and- dirt? Is there some way to accomplish this?