Today, we noticed that two of the chicks were on the ground. We first thought that they were dead, but fortunately, they were still moving. They could have just fallen out of the nest. I picked them up and placed them back in the nest. Their mother was on the nest and, she got out of the way when she noticed my hand. She did not get upset or fly away.
We then tried to fix the nest as it was tilted and quite shallow. We do not really know how they will fit as they get older because the nest is not that big to fit them all comfortably. The nest still needs fixing. I may try to straighten it or put a barrier on the side that is lower.