there is a feature called "Insert Time", I think you can find it in the Event menu, I can't remember off the top of my head and I'm not in front of my rig. Move your playback cursor to the start of your session and go Event-time operations-insert time and you'll get a window like this.
http://www.soundonsound.com/sos/jan0...rotools7.l.jpg
You can add an extra 8 or 16 bars, whatever you need, and all your automation, tempo changes, and markers will shift over with the audio.
Hope that helps