Yeah, I would probably arrange it as:

Disc One: Beginning ----> Ending of Macalania
Disc Two: Bikanel ----> Yunalesca battle
Disc Three: Sin ----> Ending

It would be difficult to split it into four though. That would be quite hard, but my attempt at it would be:

Disc One: Beginning ---> After Luca Blitz Tournament
Disc Two: Mi'hen Highroad ----> Ending of Macalania
Disc Three: Bikanel ----> Yunalesca Battle
Disc Four: Sin ----> Ending

But yeah, that's stretching it really.