How to override a file in Azure Container App container by another one ?

Hello,

I would like to override a specific config file in my ACA container.
One way would have been to use Azure Storage / File Share and volumeMounts in app.yaml, as described in tutorial :
https://video2.skills-academy.com/en-us/azure/container-apps/storage-mounts?pivots=aca-cli#azure-files
But I find that I can only mount an entire folder, that also overrides the entire folder in my container. Which is not suitable because I have other critical files in this same container folder.

Do you have any idea on how I can do this ?

Thanks,

Maxime D