I had the exact same problem when I switched to EDI and using AOB to print the Alibris packing slips. I did create a fix, but take note: I cannot guarantee that this fix will work in every situation. On top of that, it would be good for you to have some html/css knowledge, but it isn't essential.
Basically you will need to create a custom packing slip and add this markup at the top:
Code:<style type="text/css">
div table {page-break-before: always;} /* for alibris packing slip */
</style>
You will notice that I am modifying anything that is a div followed by a table. This css code puts a page break manually before every occurrence of div table Alibris packing slips *always* start with this, and it seems to occur only once in the packing slip markup. I, in my own custom packing slip, do not have this sequence of markup so it will not affect my own packing slips that AOB generates.
Hope this helps! It's not a perfect solution and, like I said, I am not 100% sure it works all the time, but it hasn't failed me yet...
Josh