My pullets are beginning to lay. I have 7 pullets. 4 are laying. They all want to use the same nest. I have two side by side. They are old milk crates. The coop is a small insulated setup in the back of a tin barn. One of the hens keeps getting into the nest when another hen is already in it and sits on the hen. Then she gets frustrated and scratches into the deep litter and makes a nest in the middle of the coop and lays an egg. What should I do?? What is wrong with my design?