How to start a new text thread/conversation with someone you have texted for years?

HuntCC wrote:

How do I start a new text conversation with a friend so that my friend will not see the new conversation appended to any previous conversation with that friend? Apple's web site instructions did not work. When I 'compose' a new text, the app automatically appends and displays this new conversation to the previous one when my friend views the new incoming text. Next I deleted the old conversation. When I created the new text, I did not see the old conversation; however, the recipient received the new text as a continuation of a previous thread. In simple terms how do two people start a new text thread such that the new text thread does not appear appended to another conversation thread which has been open for years and years. New text thread, get it? NEW TEXT THREAD - even if the recipient has been getting texts from you since the beginning of texting phones. (am I asking too much? am I the only one who values such a feature?)

Messages doesn’t support multiple threads per recipient, and doesn’t really even have a concept of threads.

Each message is self-contained, and ephemeral.

Each message sent has no connection to the other messages, or to the history.

You do see your own history of previous messages, but the recipient can have already deleted their copy of their own messages history. Or not. And you can’t change what the recipient sees here either, past the message-deletion window. They don’t see your history, and you don’t see theirs.

Your available option is to delete your own history — which effects your history but won’t effect anybody else and that whether individually or in a group — or to start a new conversation with your friend using a second and unrelated email address or number for them. They would need to have a home account and a work account, for instance, and those two carefully kept separate in your own Contacts.

Log feedback with Apple, as was also sagely suggested.

The short answer is that you don't. You can delete everything on your phone and it will appear as a new thread to you. However, you cannot delete what is already on the other person's phone. They would also have to delete the thread.

You can let Apple know it's a feature you would like to see here:

Product Feedback - Apple

I don't see the need for it personally but I'm sure you're not the only person out of billions who would like this.

Once you send a text or an email, or any other communication, whether on paper or electronically, it legally becomes the property of the recipient; you have no more say in what they do with it or how they dispose (or not dispose) of it.

Thus, Apple cannot legally let you delete content on someone else's device.