Check for existance of DNS records when transfering an account from another server

We've just completed the transfer of all accounts on a server not part of our main DNS cluster to a new server that uses our DNS cluster.

Sadly some accounts had domains since moved to their own accounts without deleting them from accounts that were just migrated.

This removed all existing DNS records for this domain, and replaced them with the old ones.

I would like the transfer tool to check for existance of DNS zones before starting the account transfer, before even putting the site offline and warning about this issue so it can be fixed manually without risking putting a site offline that should be.

I was expecting this to happen and it was rearly a surprise to find that it did not work like that. I just have to hope that I've found all the accounts it happened to :(