It seems the amount of food that a person buys is also monitored by the Government, e.g. the scene where Sunday buys food and its shown on a digital register of kind.
If this is the case, how are they even able to buy food for all the sisters ? They don't seem to suffer from malnutrition and also Cayman says something like how they've been taking someone else's food for 30 years.
How did they manage to get so much food for 30 years without raising suspicions (since is 1 visible portion and 6 hidden portions)?