Who needs malice if one can have poor software design for free.

that's a good quote. Not sure if it means much, but it sounds good and intelligent :)

I targeted "funny", but "intelligent" sounds good too.

I've had the pain of trying to do this once before when my parents got a new email address. The Apple account was never consistent thereafter, with different devices showing either the new or old email address.

We solved it once and for all by creating a new Apple ID under the new email address.

The problem with doing that is the music and the apps purchased.

I think it might be OK if you turn on family sharing and add the new Apple ID?

Being allowed to have my own email address that I bought that relates to my domain would make iCloud a lot better. But it's not all that difficult to stumble across brittle edges unfortunately, so adding more isn't going to be helpful.