Enrolled students present more often than sit-in students and are scheduled first. Students who have conflicts on particular dates or days of the week will be manually swapped with the subsequent student when assigning presentations.
from random import shuffle
enrolled = ['JL','EO','TJ','CM','VV','JC']
sitin = ['MC','TH']
shuffle(enrolled)
shuffle(sitin)
enrolled.extend(sitin)
print enrolled