Bootloader password - existing content found in /etc/grub.d/01_users

I need to set a bootloader password and am apprehensive about changing the existing config (per warning about potentially making a system unbootable).

RH documentation says to add the following lines:

cat <<EOF
set superusers="john"
password john johnspassword
EOF

The current /etc/grub.d/01_users file already has this at the top:

#!/bin/sh -e
cat << EOF
if [ -f \${prefix}/user.cfg ]; then
  source \${prefix}/user.cfg
  if [ -n "\${GRUB2_PASSWORD}" ]; then
    set superusers="root"
    export superusers
    password_pbkdf2 root \${GRUB2_PASSWORD}
  fi
fi
EOF

Should I append the first part below the existing EOF, replace the existing content altogether, or something else?