I have 10 hens about 1 year old, they lay 6-7 eggs a day .somebof them have very soft shell ,some are only soft membrane not any shell and those get eaten by hens ,some lay soft egg during the roosting and drop those with poops ,I always have available oysters shells for them ,which they don’t care to eat , purchased different calcium source like crumbles also always return all the shells from the eggs we eat ,What else can I do to give them more very needed calcium