For a product that already has chat built in and has chat history that needs to be preserved, what would be a good way to move the existing chat history(past conversations) into twilio chat ?
Twilio developer evangelist here. Our API supports importing new messages into it, which means you could import your existing chat history into channels and they would be preserved in the order your imported.
Now, notice how I said "in the order you imported". This is because our API still doesn't support overriding timestamp when the message was created. I.e. you can't pass that when creating the message.
This is a feature we are working on, and will be available in the future.
So in summary, you can import all your messages using our API, but they will only be available with the timestamp of when you imported them. We will allow you to go and update those dates in the future, but that's not something we have available at the time of writing.
Hope this helps you.