1. I read your earlier post. You should be aware that you can modify your posts. If you look at your post after you've entered it, there are tabs on the upper right hand corner of the rectangular box it appears in. Click the "Modify" tab and go to town. You can actually fix "scratch" in the post itself.
2. Doing as you've suggested would take an inordinate amount of time and effort. First, each one of these child boards would have to be manually created. Then, they would have to be populated with old posts, which is the type of sorting and categorization that's near impossible, especially given the PHP program that is this forum (I run a forum with the same code elsewhere). Finally, even if that were done, or just done away with, there's still the issue of controlling future posters. You may have noticed that threads rarely stay on topic, and they're rarely found in the correct category.
Unless a poster is diligent (or crazy) enough to go through all the relevant posts and catalogue the pertinent/important information in one single thread, which can then be stickied at the top of a particular board, your proposition is bound to be vetoed by Andrew. Not that it's a bad idea, mind you. It would be extremely useful. It's just, for all intents and purposes, impossible.