3 Blogs on 1 Installation (all need separate URLs)

I have just inherited a blog project that’s a mess. There are 3 blogs running off of 1 installation (for ease of use they say) and the blogs are being dolled out to each URL based on a selected category. This sounds good in theory but there’s one big problem. Every post has the same main URL.

Blog A – Most important and really the only one that we care about now
Blog B – Important in the future but not really important now.
Blog C – Not really important right now.

Currently all URLs are coming from Blog B, which isn’t good. If I go to Blog A and click on a post heading to view the single page, I get redirected to Blog B’s single post page. In the RSS feed of Blog A, all posts are listed as BlogB.com/category/post/. In fact, I’m pretty sure to search engines it just looks like Blog A is listing Blog B’s data.

I’m researching how to get every post to have the correct URL. It would be great if I could keep them in the same installation but I’m willing to split them up into separate installations if I need to. I just need Blog A’s posts counting for Blog A and having Blog A’s URL.

Any help or insight is greatly appreciated!