1. Create a sequence to hold your footage. (Source Sequence)
2. Add the clips, and sync them manually.
3. In the bin, right click that sequence and choose New Sequence From Clip. (Target Sequence.)
4. In the timeline, right click on that newly nested sequence and choose Multi-Camera>Enable.
and 5. In Program Monitor select wrench tool and Multi-Camera. You may be in Composite mode.