I doubt there is a way for this but, first question:
Some of my friends have iPhones and when they create a group message they get all the replies in the same thread, whereas I keep getting messages individually which turns out getting around 25 messages in my inbox... WHY? Why can't I also get all the replies in one thread? Ridiculous.
Question number 2: When I "reply all", for some reason the MMS has a default of keeping two fields, one empty, one with all the numbers and previous message sent. Can I delete this second field? Why would I want it anyways RIM?
The second box is there to allow you to add additional recipients. Not gonna delete automatically. As for the threaded messaging, not sure. SMS works that way, but have no idea of MMS.