Display linked posts together

Hey everyone!

I’m starting a project and already got stuck with a layout problem. I have 2 authors that will write about the same subject, so the whole point of the blog is to have the 2 posts shown side by side, and, even more – I’d like for these 2 posts to be treated as a single one. For example, visitors would comment on the page, not the posts individually. I hope all this makes sense..

While I want authors to be able to write individually, I want the posts to only exist while linked to one another.

I suppose I have to link the 2 posts somehow, and then use that as a condition for layout, but now sure how to get this started. Any ideas?