@Ramon
For a new TTy you will need the correct xml info and then do the centers poly thing as well as drawing the new TTy.
I forget the specifics but I'd pick a TTy and follow it through the xml adding the new name next to it. You can add the connections later but it shouldn't hurt to do it now either.
Once the xml is up to date, follow Elk's guide step by step. @thedog probably more up to date on it than I 
If need be, we'll bring in reinforcements if you get stuck 