[James Carroccio]"I would like to keep all of the footage in one project file, but how can i create multiple "TIMELINES" ?"
Replace the word "project" with "event". Put all your footage in one event. Organize your footage using keywords, including a keyword for each story line. Then create a discrete project for each story line. After you've edited them, make a compound clip of each, and intercut those compound clips into another project (your 4th now) to create your final edit.
This is what I might do. Others may have better ideas...
What used to be called a "Project" in FCP 7, is now an "Event" in FCP X.
What used to be called a "Sequence" (timeline) in FCP 7, is now a "Project" in FCP X.
So, import into Events, edit in Projects. FCP X Projects (again, these are just "timelines") are not saved inside of an Event, the two are separate. When any given Project is open, ALL Events are available to edit clips into the timeline.
It's a little weird at first, for sure.
If you don't want projects and events other than the one you are currently working on to show up when you open FCP X, download EventManagerX. Super simple design, well worth the couple bucks. Before opening FCPX, use it to choose only the project and event you want, then it opens FCP X for you (if FCP X is already open, it will just close and reopen). All app does is make two new folders in finder that FCP X doesn't look in, and move projects/events to "hide" them. You can easily do the same thing yourself, but EventManagerX handles it so well.
There is another much easier and cleaner way to work - you first need to watch John Davidson's FCPX videos, especially #2 Importing. You'll see that using Comps (compound clips) as multiple timelines works fantastic. This is the only way I work anymore and I also cut features.
Watch these videos! Everything you know about FCPX will change - for me an 18k HMI went off in my brain and I finally realized why Apple created FCPX and why we don't have FCP7 anymore...
I edited my last large project that way and wasn't completely happy. Operationally, having lots of compound clip timelines was nice, but the overall production got very sluggish towards the end. I'm not sure whether having complex timelines inside compound clips in the event was the cause, but the next big job I do will be back to primarily editing sequences as multiple projects.
To answer James' initial question, I would edit multiple projects and organize the various rough cuts inside folders in the project library window.
I've had no sluggishness yet working on a doc. I'm using comps exactly like sequences so when we change a cut I dupe the comp and keep cutting. It's easy to then delete the old cuts if we know we're not going back. I rarely used nested sequences in FCP 7 or other NLE's and I'm not using comps in other comps in FCPX. I still like to copy/paste my edits into master comp cuts so I always see all my clips. Guess that comes from over a decade of being spoiled with Sony Vegas and never getting bogged down with massive 90 min 60+ track projects. Even when Vegas added nesting I still never used it - just me I guess, my brain needs to see every bit of picture and sound.
I still say the John Davidson method is the best, this could change as FCPX evolves...