Yes! You can now add multiple subtitles within the same blog post by using the TITLE item in your blog post editor.
To the right of your blog post builder, click on the TITLE button.
This will add a section in your builder in a larger font that says "Click To Add Title Text". Click on that and enter your subtitle.
From there, click and drag your title to the section of your blog post where you'd like it to appear. Below is an example of what a subtitle may look like in your live blog post: