Is it possible to add another photo to an Instagram post after it’s already been published? If not, are there any workarounds to update a carousel without deleting the original post and losing the likes and comments?
No, Instagram does not allow you to add photos to an existing post after publishing — not even to a carousel. The only native edit options are caption, alt text, and tagging.
The only real workaround is to delete and repost, but you’ll lose all engagement. To minimize loss, screenshot your comments beforehand and consider reposting during a high-traffic window to rebuild reach faster.