Make it possible to update or add CNAME on an existing domain. To be able to add any needed CNAME record including Envelope-from.

(Finding regarding existing domain with TXT record (and one or two CNAME records) and attempting to add Envelope-from, is that one HAVE TO DELETE all existing records of that domain and the domain from then entity in order to be able to add Envelope-from or any other CNAME record. Then one has to create a new record for the domain and a brand new TXT-record Value is created.)