Well...
it is not a very good idea to house three snakes together. You cant tell if they are having conflicts, and this causes irritation. Another thing is after about a year they might start to TRY and breed, but the female woukd not be developed yet, the eggs would get stuck in her, and she would die. If you decide you want to try and keep them together anyway, make sure they all are the same size because then canniballism plays into the picture. It is recommended that for one corn should be a 20 gallon tank. That will last it at least 3.5 years. Hope this Helps!!!