Sorry Peter, I wish it was simple to split threads but it isn't. I'd end up butchering it and loosing too many posts. The software will allow me to break a thread at a certain point but not allow me to pick and choose which replies to apply to each new thread.
My suggestion is to either keep this one as is - I view most topics on TM as a logical progression rather than one topic that stays rigid - or start a new one and simply cut and paste the posts you want to have in the new topic (I can help with this if you wanted).
