Let the eggs set so the air sacks move back up to the big end of the egg. So store pointy end down. After shipping they could have become displaced a bit. I believe it takes about a day. Others may chime in. Carefully remove the one she has been sitting on. If you leave it it will hatch first too soon for the others and by the time they are ready to hatch she will be long gone teaching the first born the ropes. But leave the egg or some falsies to keep her focused till your new eggs arrive. Dont worry she will stay broody because chickens cant tell time. Then Mark the new eggs with pencil so you know which ones are which and set them one by one in front of her, She will carefully shovel it under her and put it in just the right spot. Then put another down in front of her. one by one she will put them under her. Remember the day you set the eggs is Day Zero. The 21 day incubation starts when they come up to temperature. deb