Moving accounts to a new Server

ok here are my answers to your questions, I hope this is clear-

The /backups directory on the new Server contains these files-
(23 files, 7 accounts from old Server)
Examples-

.dj.tar.gz
virtualmin.tar.gz
.dj.tar.gz.dom
virtualmin.tar.gz.info
.dj.tar.gz.info

I got the command sequence from this post-

I activated a spare license for Virtualmin on the new Server.
Had previously overlooked this command, but ran it-
sudo virtualmin restore-domain --source /home/xadmin/backups/virtualmin.tar.gz --all-virtualmin

Result-
Restore completed successfully.

Then ran this command-
sudo virtualmin restore-domain --source /home/xadmin/backups/ --all-domains --all-features

And got this response-

Checking for missing features ..
.. WARNING - The following features were enabled for one or more
domains in the backup, but do not exist on this system. Some
functions of the restored domains may not work : Apache website, Apache SSL website

Checking for errors in backup ..
.. this backup cannot be restored : Original parent virtual server <redacted>.com.au does not exist

FYI- the Apache errors are expected, I am attempting to change from LAMP to LEMP stack.

YES- all the domains are registered and working properly on the old Server
YES the original parent server is in the backups

I think @jimr1 is closest to a solution, but I do not understand the restrictions- if I’ve got a backup of the parent domain, why do I still get the error?

Any assistance appreciated