Nextcloud child dataset mounting problem

I need some help. I had set up TrueNAS and Nextcloud years ago, when everything was new to me. Now I am trying to move Nextcloud hosting to new server, but keep data in TrueNAS still with NFS sharing.
I have /mnt/pool/Data dataset mounted to /mnt/pool/iocage/jails/nextcloud/root/mnt/Data for the Nextcloud plugin.
But I also had created child datasets inside the Data dataset - named for each user. Now when checking all of those directories - only the /mnt/Data inside the jail shows data. Each user directory under /mnt/Data is like it is supposed. But all of the TrueNAS datasets show as empty.
In Nextcloud I have used external storage plugin to create folder per each /mnt/Data/ user directory.
How can I get fix this mess and get everything mounted properly now, so I would have actual data to share in a TrueNAS dataset? I am afraid to delete the child datasets also.
I want to stop using the Nextcloud plugin and jail, so I can’t share out the /mnt/pool/iocage/jails/nextcloud/root/mnt/Data.

Thanks in advance