Hello, can anyone let me know whether it's possible to add a "call to action" website block (or just a button) to the header section of a specific blog series?

I have 4 different blog series, and I'd like to include a call to action button for only one of them. When I try to add a website block, it will only add it at the bottom of the page and then it shows for all my blog series. What I would really like to do is add a button into the blog series header, but I can't see a way to do that (only edit the text, background colour etc.).

I'm using v14 enterprise on SaaS.

Thank you!