In what ways can we modify the subject line in gmail while keeping it in the same Conversation thread? So far, I've learned of one way: When I subscribe to a mailing list, and I get a reply back the text in bracket doesn't change the conversation.
Example:

   bigger attachments
   Re: [gmail-devel] bigger attachments

Both of the above will be saved in the same conversation thread.

If you know of other ways to keep messages in the same thread, let me know.

Thanks!