As a general matter, the player controls itself via the ID3 tags for the files. Make sure that the Album/Book ID3 tag for the files is identical (e.g. not including a Disk number, which would cause the player to think that this is a different book)–the player, then, should see all the files as from the same book and then will be guided by the track numbers in moving from one file to the next (and so, make sure that all the tracks, including from one disk to the next, are in a single sequential series). I think that this should do it for you–
If you need a good ID3 tag editor, Internet freeware MP3Tag is highly regarded. http://www.mp3tag.de/en/
P.S. If you found this info. helpful, feel free to give me a 1-click (free) Facebook vote in a local restaurant photo contest. The info. (posted here in the SanDisk forum): http://forums.sandisk.com/t5/Anything-goes/Help-fellow-forum-er-out-amp-win-local-photo-contest-with-a/td-p/290426
