A good solution would be to go to your CMS collection editor for your Blog Posts, add a new toggle field that says “include form” or something similar, and then add your form on your CMS collection page for the Blog Posts. For the parent element of the form, go to the settings in the CSS/styling panel, go to conditional visibility, set it to only show if that CMS field is toggled on. So only one of your Blog Posts would have this toggled on. That way, the form will only show on the one Blog Post, but you could turn it on for others in the future if needed.
If this makes sense, awesome! if not, drop your read-only link, and I can help show you what I mean.
Good luck! And if you reply to this post, please @myonke me, so I get a notification and can come back to this thread!