How are you supposed to update a subdomain-ID’s ZoneFile, if you own it? (Or do you even own it as it is managed by the name itself, in this case id.blockstack?)
I can see in the CLI there is a register_subdomain command, but is there a possibility of an update_subdomain command?
This is supported by the subdomain protocol, but the subdomain registrar doesn’t yet broadcast zone file updates for subdomains (the code simply isn’t written).
However, any on-chain name can broadcast a newer zone file for an off-chain name. For example, you could:
michaelfedora.id that includes a newer zone file record for michaelfedora.id.blockstack,NAME_UPDATE for michaelfedora.id
To do so, you simply create another TXT record like the one that encodes your .id.blockstack name, give it the next sequence number (the seqn= field in the TXT record), and sign the record with your private key. You can see a working example in this integration test.