Changing multiple sprite alpha

Hello!
I'm making character visualization system that looks like typical 2d visual novel. I want to make characters smooth appear/disapper using transparency. But there is a problem. Character sprites built using multiple layers like: body, eyes, mouth, cloth, accessories. At first I tried to create main character GameObject with SpriteRenderer and body sprite and child GameObjects with other layers. All looks good until I try to dissolve character - when changing alpha of body, cloth and other layers simultaneously, at some point I can see body under clothes.

Is there any way to dissolve group of sprites without exposing underlaying sprites?

Currently I trying to combine all layers in custom shader but I don't have enough experience with shaders and I am not sure that it's a best approach.