How to superimpose two animations using the animator?

We are making a 2D game with sprite objects. In our current project, we have two animations, one for a character and one for a transparent effect to be played on top of the character when tapped. We're having trouble with how to do this in the animator. We've tried putting both animations on separate layers and trying any combination of override/additive for both, but every time we tap the character, the effect animation seems to completely replace the character animation we want superimposed below the effect.