Additional users after openssh-server installation

I want to use the openssh-server container as an sftp server and saw that the first user can be added during installation using:

-e USER_NAME=username
-e USER_PASSWORD=password

What is the correct way of configuring additional users after the container has been installed?

Thanks

It was designed for a single user access. For multiple users, you can run multiple containers. It’s what I do. That way, I can have different access settings and volume mappings for each user.