The Add-On domains or Parked domains will be preset in /etc/userdomains. But they are not listing in cPanel, like Email account creation tab. This is mainly because of the XDNS entries in /var/cpanel/users/<cpanel_username>
If your required domains are marked as XDNS, then rename XDNS to DNS of all the required domain entries. After this you have to run the following script to update the userdomains
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#scripts/updateuserdomains===
After running this script, the domains will be found available for new account creation. Also the previously created accounts will be restored back.
