Mecanim 'Locking' my facial blendshapes

I have an animator component that controls blendshapes on a model’s face. This animator is working fine for lipsyncing different animations, and only affects 7 out of the 28 blendshapes on the face.

I want to control the other 21 blendshapes independently of the mecanim system - making the eyes blink randomly, eyebrows arch in surprise etc. To my surprise, I could not change any of the other blendshapes while the mecanim animator was active. Only after setting animator inactive could I get the blendshapes to change. This occurs even when playing an empty node in the mecanim animator.

Is there something I am missing here? I don’t think baking random blinking into hundreds of dialogue animations is a solution, and it probably won’t achieve the desired effect also. Animation blending is not the correct solution as well because the desired effect is not a blending effect.

How can I change unaffected blendshapes (like eyelids) manually when the mecanim animator is active on the face?

I finally got back to researching it, and I’m going to answer my own question after a few months. haha

In the animator window, using multiple animation layers with the blending mode set to ‘additive’ will combine animations.

I had a similar problem with a single blendshape out of 20+ blendshapes that my skinned mesh had. It was happening because one of my animations inside the animator controller modified that blendshape. The blendshape was locked even if that particular animation was not playing at the moment. What I did was opening that animation with the animation window (ctrl+6) and removing the change to the blendshape. That made the blendshape be unlocked for that animator controller.