Click on some event on the timeline to select it. While holding down the Ctrl key click on the events you want to "group" then right click and select group so you can move them around or work on them as a group. I just push them to the overlay track and drag them to beyond the end of the timeline till you're ready to put them where you want them.

Remember an event is a scene (file) you drag to the timeline or one you make by using the split event option on the Edit Menu which will chop up a long timeline into managable pieces.