Gents, I just came across this post while looking for something else.
You can change the number of payload schedules by changing the following variable. You must be in a controlled start to make the change.
In controlled start go to $PLST_SCHNUM and change it to the number you need. Do a cold start and let the robot boot up. Go back into a controlled start and verify that $PLST_SCHNUM and $PLST_SCHMAD are both set to that number. Go back into a cold start and check the number of available payload schedules. I don't know what the max number you can have is; I've been up to 64.