Thanks to Adam and Jay for their knowledge and understanding of the multicam edit .

Next question:
I did a three camera shoot of a graduation last Friday night and I want to do a split screen of the two lines of graduates coming into the venue at the same time. How in the world do I do that in the multicam edit monitor with three lines of video? How can I pick two out of three???
Maybe since that part is at the very front of the graduation exercises, I could do that split screen before I start using the multicam edit feature???

EDIT: I just found one answer and I think I understand it. I'll just complete the multicam edit and then go back and put the second cam video track above my multicam edit final choice. So I will select one of the two tracks for the entire part where they are coming in, and then I'll go back and place the second cam on a video track above......
Hummmm, will I be able to crop both video tracks then?????

That's right; you'll crop or resize each track after they are stacked in your multicam sequence. You might have some challenges keeping them in sync.

Depending how long this split-screen portion is, you might want to do it as a separate sequence (i.e. not multicam)

But if it's just a short bit... I haven't done this, but I'd try it this way (and this might not work): You've got a rough multicam edit done. It's a single line of video on video track 1. Let's say for your split screen you want to use cams 2 and 3, and there is a place in your video track where you are cutting back and forth between them where they are both doing what you want them to; the grads are walking in. I would just grab a CAM2 clip and drag it up a level to track 2 and stretch it out for the duration you want. Then stretch a CAM3 clip out to fill the gap in track one, deleting other clips on that track to make room as necessary. So now both are filling the correct time and are in sync. Now all you have to do is crop or resize them to fit.

I think. There's probably a better way.

Thanks Adam. I'll give that a try.......