When you go to your post, you have the option to turn a published post into an “anonymous” one, which means the post will be hidden from public view unless the URL of the post is shared publicly.
Once a post is made anonymous, you can go ahead and make the necessary edits and then proceed to publish it back in your main blog. I hope this is what you’re looking for. If not, need to wait till Matt or other experienced users to get back to you.