Use the import tools you have with the blog originaly ?
It won’t be easy, since – I assume – in all the 3 blogs there are posts with the same ID (e.g. 1, 2, 17…) so you have to think how to overcome that challenge. I didn’t really see any “tool” for doing that. Sorry, and I don’t envy you 🙂
It wouldn’t be incredibly hard to write a tool to do this, but I don’t know if any exist yet.
Wow, this would be a great help. I have the same situation as I have old WP installs (that I installed … ) using multiple installs in the same database (different prefixes). Now I need to merge them into one and I usually end up just cutting and pasting (!) from one to the other. I have tried exporting to another format (e.g. MovableType) and then importing into the new WP and that worked OK, but a WP-export then WP-import would be great.
