I’m playing around with creating Blend Shapes through script.
All works fine, and the changes to the mesh (since I’m accecssing it via .sharedMesh) even stick around from run to run within the editor.
But now I’m wondering: is there any easy way to get Unity to write these newly added blend shapes to disk, so they’re still there when I save & reload the scene?
There has to be because MCS and UMA exist - unless they are doing some type of min-max thing, but I don’t think that is how they work because custom characters would need min-max mesh files to be used in the systems. Well UMA can have custom characters, MCS is locked down - to my knowledge.
This link may help a little - maybe.
UMA doesn’t use blend shapes; it just scales bones (or at least, that’s my understanding).
MCS does use blend shapes, but it doesn’t (as far as I know) edit those blend shapes within Unity; it just loads them from files. I know how to do that. It’s the saving that I’m not sure about. I suspect that, like many other things in Unity, there is an importer for these, but no exporter.
Hey! Did you ever end up figuring out how to achieve this? 
EDIT: Nvm! Just found Blend Shapes are saved when using Unity’s FBX Exporter tool! Problem solved!
!! Thanks for pointing that out! That does indeed appear to be the solution we’ve all been waiting for.