Vertex Animation and External Face Mesh Morphing?

I took the face mesh template into 3ds Max and added a little vertex animation. If I export that mesh it loads into Lens Studio with the vertex animation correctly. (Animation Mixer providing the vertex animation... perfect!)

However, I need the face to also inherit the face tracking deformations.

It looks like I can only reference a static mesh in the Face Mesh's [External Mesh] target.

Is what I'm trying to do possible? My next alternative idea is to export each keyframe of the external mesh as a morph target and create a controller to animate through the "morph targets" 1 frame per frame. But that seems very hacky.