same, keep finding myself wanting to do this. you can continue a thread with X, by pasting the link to the last tweet, but it won't update the threads posted to other platforms like Threads and Bluesky.

would be great if you could paste a link for each platform, ideally you should be able to continue a thread by clicking a button on the published post in the sidebar, and Typefully locates the thread, and figures out which post to reply to