The trick to keeping the corn tortillas from breaking is to heat them up a little bit.  When they are heated they become more pliable, thus easier to roll without breaking.     I've heard it recommended to cook them in a bit of oil or sauce before adding the filling and rolling them up,  but I find they get too soft when prepared this way.    Another method is to heat the tortillas all at once in a microwave before rolling them.  However, it’s my experience that as they cool off they lose their elasticity and start to break again.    My recommendation for the best method to heat up tortillas to make enchiladas is to cook them in a lightly oiled pan 1-2 at a time.  Once they’re heated remove them, and then roll those up quickly while you heat 1-2 more in the pan. Keep repeating this process until you get all the enchiladas rolled up.