Thanks for reaching out, and sorry for the late reply. I missed your original message.
No, it wasn’t possible before—now it is. Now you can use --fpm-admin-value to force the admin value to be written, or --fpm-value to force the user-level value to be written. If not set, it will default to existing logic, meaning it will preserve whichever value type exists.
You can use the following patch to make it work now: