Split video screen into 3 equal parts
Edit your footage in one timeline, with the sequence setting set to the combined dimensions of all the screens (so the width of one screen across × three times the height). So if they're 1080p screens you'll be looking at 1920 × 3240.

Now make three sequences, each with the resolution of one playback screen, e.g 1920 × 1080. Take your original sequence and lay it into these timelines (as a nested sequence).

Adjust the motion properties of the clip in the first sequence so that the top of the clip lines up with the top of the frame, then in the next sequence align the middle of the clip with the middle of the frame and in the last sequence align the bottom of the clip with the bottom of the frame.

Now you have three sequences that align as you wish. The beauty of nesting the combined sequence is that you can make changes without having to synchronise three separate sequences.