Uniform low opacity on multiple layers

Hi, so I am making a character to be used for animation and I just ran into a problem. The character has no head or neck and is just a face on a body. They are supposed to be see through. I also put different facial features on different layers to make everything easier. However, when I lower the opacity on either the layer or the material using the opacity modifer, there is a darkened overlap between fill layers. I tried to do this without fills for the nose and mouth, but then I realized because the mouth is so big, it comes over the bow the character is wearing, so I need to have a fill color. Is there a way to create this semi see through character in blender with a uniform opacity so that there is no overlap?