I love conversation view, but I hate the fact that I have no way of manually "breaking" a conversation when Gmail guesses incorrectly, or more generally, when I

I love conversation view, but I hate the fact that I have no way of manually "breaking" a conversation when Gmail guesses incorrectly, or more generally, when I want to logically group a set of messages together. A real example that I work with a lot: I agree to buy something from someone on a forum. I have a series of transactional emails from the forum about the topic, possibly a paypal receipt, and a UPS ship notice. Creating a whole label for that transaction is overkill (I don't need to "name" the transaction, and label sprawl is already fairly unmanageable): I just want a way to correlate those messages together for quick review later. I can't do that today, and worse, I've occasionally had cases where Gmail creates a "conversation" out of several Paypal receipts, all for unrelated items. Like I said, I love the idea of conversations. I just wish I had more control over them.