Hi aedan.d,
The idea of expressions with Moves By Maxon is to provide the recorded “parts of the face” when those parts move, leading to combinations of one or several to the representation of expressions. Single Blend Shapes are not full expressions. For non Moves by Maxon meshes, this per PoseMorph Pose has to be created newly, while it can then use the recorded information when those parts move.
When and how long these parts are moved is typically available (thinking about our last forum thread between us), but the expression for your Character Creator 3 (CC3) needs to be created on your side after identifying what each Moves By Maxon moves in the provided mesh.
In detail, the list in PoseMorph needs to be populated with the point movements for your mesh.
Some ideas were discussed here:
https://www.cineversity.com/forums/viewthread/3961/
PoseMorph works here on a point position level. This requires a 100% match of the points and their ID number. I have no experience with CC3 nor have a file here at all.
All the best