I see the spot for appending commands whenever a domain is changed, however, I use external DNS hosting which allows me to use a simply http API to create my DNS domains.

What I do right now is this: I use virtualmin to handle my DNS internally, but I have the external company setup as slaves to my master. Once I've created the domain in virtualmin, I run a simple WGET command (although, there are tons of other ways to do this) which creates the secondary domain on their servers. Getting my DNS to do the notify and allow transfer settings is very easy. It's just the onetime command on creation and deletion that I want.

If there's an environment variable set or some other way for me to tell via bash-script that a domain is being created or deleted (NOT modified!), then I can easily enough create the script.

FWIW, the command I'm using, (obviously sanitised) is:

wget https://www.nettica.com/DNS/DnsApi.aspx?U=MY_USERNAME&P=MY_ENCODED_PASSWORD&CMD=createsecondary&D=DOMAIN_TO_CREATE&M=MASTER_SERVER_NAME&MIP=MASTER_IP

if I can help any further, please let me know!