Oh, whoops! How could I forget "The Enemy Within?" I didn't check the list in The Music of ST
So yeah, that's four scores remaining, three of which were fairly complete or at least moderately long. (The "Shore Leave" release on GNP's Volume 3 is 17:47 worth of music.) I don't think they can all fit on Disc 4. Probably Disc 5 will have at least one episode score plus the extras.