I'm not sure what you mean. I'm aware there are more hatcheries. I spoke with the manager where I shop and was told it was Townline. I spend most of my money there, because they're very nice.
I'm not aware of any agreed upon quantities, they don't tell me everything.
Different chick sellers buy from different hatcheries, because I also have Country Max and they order special.
I recently purchased a 1974 issue of Mother earth from back in the day when hatcheries guarded things very tightly. It was interesting.
Each store is receiving from 3-4 hatcheries not just one.