So there's sort of a bug if you add upload a picture and check the box to "Allow image to be displayed in public directory template" then click upload. If you do that it makes it a separate image instead of a reply.
My work around for that is if I have a picture I want to use and also save to "My Templates" by adding it to the public directory, I go to the top of any page, click the create button and select "Caption A Meme or Image" Then go through the process of clicking Upload your own image, checking the box to have it be in the public directory template. Once you've done that it will be in your "My Templates" tab on your reply box. So I'm guessing the steps you've already done, if you reply again it should be in your "My Templates" already!